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15.3.3 Correlative or Reciprocal Nature of Rights and Duties Under the Law of
Neutrality. The rights and duties of belligerents and neutrals under the law of neutrality may be
understood as correlative or reciprocal.
The duties of neutrals often correspond to rights of belligerents, and rights of neutrals
often correspond to the duties of belligerents.77 For example, the duty of a neutral to abstain
from hostilities is also a right of a belligerent not to have its adversary aided in hostilities by the
neutral State. The right of a neutral State to have its territory be inviolable is also a duty of
belligerent States to avoid conducting hostilities in neutral territory.
Similarly, the ability of a neutral to assert its rights may depend on whether it has
fulfilled its corresponding neutral duties.78 For example, the right of a neutral State to have its
territory be inviolable may not be asserted to the extent it has failed in its duty to ensure that its
territory is not used as a base of operations by a belligerent.
In light of the correlative nature of the rights and duties of belligerents and neutrals under
the law of neutrality, a single rule in the law of neutrality may reflect multiple rights and duties
of both belligerents and neutrals. For example, hostile acts are not to be committed on neutral
territory. This rule involves the right of the neutral State for its territory to be inviolable, and
involves a duty on the part of the neutral State to prevent such acts. This rule also reflects a duty
of the belligerent State to refrain from such acts, and a right of the belligerent State not to have
such acts conducted by an opposing belligerent.
15.4 REMEDIES FOR VIOLATIONS OF NEUTRALITY LAW
15.4.1 Distinction Between Violations of Neutral Duties and the End of Neutral Status.
Violations of neutrality by belligerent or neutral States should be distinguished from the end of a
material, and the like, and the sending of clothes and money to prisoners of war, can never be construed as acts of
partiality, even if these comforts are provided for the wounded and the prisoners of one belligerent only.”).
76 LESLIE C. GREEN, THE CONTEMPORARY LAW OF ARMED CONFLICT 269 (2nd ed., 2000) (“Frequently, as has been
seen in the discussion concerning protecting powers, a neutral power is appointed to represent the interests of one
belligerent in the territory of the adverse party or for some of its nationals to be appointed to the Fact Finding
Commission called for in Protocol I in relation to the investigation of alleged breaches of the law of armed conflict.
In neither case can a belligerent suggest that such action is in breach of the obligations of neutrality.”).
77 TUCKER, THE LAW OF WAR AND NEUTRALITY AT SEA 203 footnote 14 (“It is also helpful to observe that the duties
of a neutral correspond to the rights of a belligerent, and that the rights of a neutral correspond to the duties of a
belligerent. The neutral’s duty to observe a strict impartiality corresponds to the belligerent’s right to demand
impartiality on the part of the neutral. At the same time, the neutral has a right to demand that the belligerent will
act toward it in such a manner as to respect its position of impartiality, and there is no question but that the
belligerent is under a duty to do so.”).
78 G. SHERSTON BAKER, II HALLECK’S INTERNATIONAL LAW 305 (28.1) (1908) (“The rights and duties of neutrality
are correlative, and the former cannot be claimed, unless the latter are faithfully performed. If the neutral State fail
to fulfil the obligations of neutrality, it cannot claim the privileges and exemptions incident to that condition. The
rule is equally applicable to the citizens and subjects of a neutral State. So long as they faithfully perform the duties
of neutrality, they are entitled to the rights and immunities of that condition. But for every violation of neutral
duties, they are liable to the punishment of being treated in their persons or property as public enemies of the
offended belligerent.”).
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State’s neutral status. Rather, whether violations of neutrality result in the end of the neutral
status of a State may depend on the national policies of that State and the belligerent States.79
Acts that are incompatible with the relationship between the neutral State and a
belligerent State under the law of neutrality need not end the neutral State’s neutrality and bring
that State into the conflict as a belligerent. For example, despite Vichy France’s violations of its
neutral duties during World War II and despite the Allied invasion of French North Africa,
diplomatic relations persisted between the United States and France during World War II.80
15.4.2 Belligerent Use of Self-Help When Neutral States Are Unable or Unwilling to
Prevent Violations of Neutrality. Should the neutral State be unable, or fail for any reason, to
prevent violations of its neutrality by the forces of one belligerent entering or passing through its
territory (including its lands, waters, and airspace), the other belligerent State may be justified in
attacking the enemy forces on the neutral State’s territory.81 This view has been reflected in the
military manuals of other States.82 For example, consistent with the jus ad bellum requirements
79 Refer to § 15.2.1.1 (Application of the Law of Neutrality and the National Policies of States Towards an Armed
Conflict).
80 DWIGHT D. EISENHOWER, CRUSADE IN EUROPE 86-88 (1997) (“Vichy France was a neutral country and during the
entire period of the war the United States had maintained diplomatic connection with the French Government.
Never, in all its history, had the United States been a party to an unprovoked attack upon a neutral country and even
though Vichy was avowedly collaborating with Hitler, there is no doubt that American political leaders regarded the
projected operation, from this viewpoint, with considerable distaste. … The Allied invasion of Africa was a most
peculiar venture of armed forces in the field of international politics; we were invading a neutral country to create a
friend.”).
81 1956 FM 27-10 (Change No. 1 1976) ¶520 (“Should the neutral State be unable, or fail for any reason, to prevent
violations of its neutrality by the troops of one belligerent entering or passing through its territory, the other
belligerent State may be justified in attacking the enemy forces on this territory.”).
82 2004 UK MANUAL ¶1.43a (“Neutral states must refrain from allowing their territory to be used by belligerent
states for the purposes of military operations. If a neutral state is unable or unwilling to prevent the use of its
territory for the purposes of such military operations, a belligerent state may become entitled to use force in self-
defence against enemy forces operating from the territory of that neutral state. Whether or not they are so entitled
will depend on the ordinary rules of the jus ad bellum.”); 2006 AUSTRALIAN MANUAL ¶11.8 (“As a general rule of
international law, all acts of hostility in neutral territory, including neutral land, neutral waters and neutral airspace
are prohibited. A neutral state has a duty to prevent the use of its territory as a sanctuary or a base of operations by
the belligerent forces of any side. If the neutral state is unable or unwilling to enforce effectively its right of
inviolability, an aggrieved belligerent may resort to acts of hostility in neutral territory against enemy forces,
including warships and military aircraft, making unlawful use of that territory. Belligerents are also authorised to
act in self-defence when attacked or threatened with attack while in neutral territory or when attacked or threatened
from neutral territory”); 2001 CANADIAN MANUAL ¶1304(3) (“A neutral state is permitted to resist any attempted
violation of its borders by force and such resistance does not make the neutral a party to the conflict. If enemy
forces enter neutral such territory and the neutral state is unwilling or unable to intern or expel them, the opposing
party is entitled to attack them there, or to demand compensation from the neutral for this breach of neutrality.”);
2002 GERMAN COMMANDER’S HANDBOOK: LEGAL BASES FOR THE OPERATIONS OF NAVAL FORCES ¶232 (“On the
one hand, the parties to the conflict are obliged to respect the inviolability of neural [sic] territory, neutral
internal waters, neutral territorial seas and the neutral airspace above these areas. Within and above these areas
all hostilities, that is the use of armed force and of other measures of maritime war (including measures based on the
law of prize) are prohibited. There is one exception to this principle which applies to measures of self-defence,
that is the event that one of the parties to the conflict is attacked or endangered to be attacked in these areas. On the
other hand, a neutral state is obliged to prevent the parties to the conflict from misusing these areas as sanctuary or
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for self-defense, belligerent forces may act in self-defense when attacked or threatened with
attack from enemy forces unlawfully present in neutral territory,83 including by taking
appropriate action to counter the use of neutral territory as a base of enemy operations when the
neutral State is unwilling or unable to prevent such violations.84
15.4.3 Neutral State’s Use of Force to Defend Its Neutrality. A neutral State may also
engage in self-help to prevent violations of neutrality on its territory. Such self-help is also an
obligation of the neutral State.85
The fact that a neutral State resists, even by force, attempts to violate its neutrality cannot
be regarded as a hostile act.86 For example, a State whose territory is adjacent to a theater of war
normally mobilizes a portion of its forces to prevent the forces of either belligerent from entering
its territory, to intern such persons as may be permitted to enter, and generally to carry out its
base of operations. If it is unwilling or unable to do so, the other party to the conflict is entitled to take all
measures necessary to terminate the misuse of neutral territory or neutral waters.”).
83 2007 NWP 1-14M ¶7.3 (“If the neutral nation is unable or unwilling to enforce effectively its right of
inviolability, an aggrieved belligerent may take such acts as are necessary in neutral territory to counter the activities
of enemy forces, including warships and military aircraft, making unlawful use of that territory. Belligerents are
also authorized to act in self-defense when attacked or threatened with attack while in neutral territory or when
attacked or threatened from neutral territory.”).
84 For example, Richard Nixon, Address to the Nation on the Situation in Southeast Asia, Apr. 30, 1970, 1970
PUBLIC PAPERS OF THE PRESIDENTS 405, 406-08 (“American policy since then has been to scrupulously respect the
neutrality of the Cambodian people. … North Vietnam, however, has not respected that neutrality. For the past 5
years—as indicated on this map that you see here—North Vietnam has occupied military sanctuaries all along the
Cambodian frontier with South Vietnam. Some of these extend up to 20 miles into Cambodia. The sanctuaries are
in red and, as you note, they are on both sides of the border. They are used for hit and run attacks on American and
South Vietnamese forces in South Vietnam. These Communist occupied territories contain major base camps,
training sites, logistics facilities, weapons and ammunition factories, airstrips, and prisoner-of-war compounds. …
[T]his is the decision I have made. In cooperation with the armed forces of South Vietnam, attacks are being
launched this week to clean out major enemy sanctuaries on the Cambodian-Vietnam border. … This is not an
invasion of Cambodia. The areas in which these attacks will be launched are completely occupied and controlled by
North Vietnamese forces. Our purpose is not to occupy the areas. Once enemy forces are driven out of these
sanctuaries and once their military supplies are destroyed, we will withdraw.”); SPAIGHT, AIR POWER AND WAR
RIGHTS 434 (“Justifiable entry of neutral jurisdiction.—The international law of neutrality is based on the
principle that neutral States exclude both belligerent parties from entry into or passage through their territory. If that
condition is not fulfilled, to advantage of one party and the detriment of the other, the latter is entitled, after protest,
to take the action necessary to protect his interests. He is entitled to follow his enemy into neutral jurisdiction and to
attack him there. It was for this reasons that Japan was able to justify her action in 1904 in cutting out the Russian
cruiser Reshitelni from the Chinese harbor of Chifu when it became apparent that China was unable or unwilling to
disarm the vessel in accordance with the requirements of international law. It was on the same principle that the
British intervention in Syria in 1941 was justifiable. The Vichy authorities there were allowing German aircraft to
use the Syrian airfields, and such use was particularly damaging to British interests at that time, in view of the revolt
in Iraq.”).
85 Refer to § 15.3.2.2 (Duty to Prevent Violations of Neutrality Within Its Jurisdiction).
86 HAGUE V art. 10 (“The fact of a neutral Power resisting, even by force, attempts to violate its neutrality cannot be
regarded as a hostile act.”).
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duties of neutrality.87 Such military operations are not regarded as hostile acts against the
belligerent State.
15.4.4 Redress of Certain Violations of Neutrality. In addition to the obligations to
prevent violations of neutrality, a State may also have obligations to redress violations of
neutrality that have been committed.
For example, violations of the law of neutrality may result in liability for payment of
damages in certain cases.88 As a case in point, if harm is caused in a neutral State by the
unauthorized entry of belligerent forces, the offending State may be required, according to the
circumstances, to respond in damages.89
Similarly, when a ship has been captured in the territorial waters of a neutral State, the
neutral State must employ, if the prize is still within its jurisdiction, the means at its disposal to
release the prize with its officers and crew, and to intern the prize crew.90 If the prize is no
longer in the jurisdiction of the neutral power, the captor State, on the demand of the neutral
State, must liberate the prize with its officers and crew.91 The neutral State has a duty to make
this demand.92
15.5 PROHIBITION ON THE USE OF NEUTRAL TERRITORY AS A BASE OF OPERATIONS
Neutral territory (including neutral lands, waters, and airspace) may not be used as a base
of operations against belligerent forces.93 For example, belligerent States are forbidden to use a
87 1956 FM 27-10 (Change No. 1 1976) ¶519 (“In order to protect its neutrality, a State whose territory is adjacent to
a theater of war normally mobilizes a portion of its forces to prevent troops of either belligerent from entering its
territory, to intern such as may be permitted to enter, and generally to carry out its duties of neutrality.”).
88 Refer to § 18.16 (Compensation for Violations of the Law of War).
89 1956 FM 27-10 (Change No. 1 1976) ¶515 (“If harm is caused in a neutral State by the unauthorized entry of a
belligerent, the offending State may be required, according to the circumstances, to respond in damages.”).
90 HAGUE XIII art. 3 (“When a ship has been captured in the territorial waters of a neutral Power, this Power must
employ, if the prize is still within its jurisdiction, the means at its disposal to release the prize with its officers and
crew, and to intern the prize crew.”).
91 HAGUE XIII art. 3 (“If the prize is not in the jurisdiction of the neutral power, the captor Government, on the
demand of that Power, must liberate the prize with its officers and crew.”).
92 William H. Taft, Proclamation Regarding the Hague XIII, Feb. 28, 1910, 36 STAT. 2415, 2438 (“And whereas the
Senate of the United States of America by its resolution of April 17, 1908, (two-thirds of the Senators present
concurring therein) did advise and consent to the adherence by the United States to the said Convention with the
reservation and exclusion of its Article 23 and with the understanding that the last clause of Article 3 of the said
Convention implies the duty of a neutral power to make the demand therein mentioned for the return of a ship
captured within the neutral jurisdiction and no longer within that jurisdiction; And whereas the President of the
United States of America, in pursuance of and in conformity with the aforesaid advice and consent of the Senate,
did, on the 23rd day of February, 1909, declare the adherence of the United States to the said Convention;”).
93 Consultative Meeting of Foreign Ministers of the American Republics, Final Act of the Meeting: V General
Declaration of Neutrality of the American Republics, ¶3, Oct. 3, 1939, 1 DEPARTMENT OF STATE BULLETIN 326, 327
(Oct. 7, 1939) (The American Republics resolve “[t]o declare that with regard to their status as neutrals, there exist
certain standards recognized by the American Republics applicable in these circumstances and that in accordance
with them they: (a) Shall prevent their respective terrestrial, maritime and aerial territories from being utilized as
946
neutral State’s ports and waters as a base of naval operations against their adversaries,94 and a
neutral State has a corresponding obligation to prevent such use.95
The prohibition against the use of neutral territory as a base of operations extends to any
hostile expeditions against a belligerent State, and thus includes such expeditions by non-State
actors.96 For example, a neutral State has an obligation to prevent the arming of any vessel
within its jurisdiction that is intended to engage in hostile operations against a State with which it
is at peace and to prevent the departure from its jurisdiction of any vessel intended to engage in
hostile operations that has been adapted entirely or partly within such jurisdiction for use in
war.97
The prohibition on the use of neutral territory as a base of operations includes
prohibitions against (1) outfitting hostile expeditions with supplies and services; (2) recruiting
forces in neutral territory; (3) establishing military communications facilities in neutral territory;
and (4) moving belligerent forces or convoys of military supplies on land.
15.5.1 Prohibition on Outfitting Hostile Expeditions With Supplies and Services for a
Belligerent From Neutral Territory. It is forbidden to permit the use of the neutral State’s
territory for the fitting out of hostile expeditions.98 As a case in point, a belligerent State’s
warships may not make use of a neutral State’s ports, roadsteads, and territorial waters to
bases of belligerent operations.”); 1955 NWIP 10-2 ¶442 (“Belligerents are forbidden to use neutral territory,
territorial sea, or air space as a base for hostile operations.”).
94 1928 PAN AMERICAN MARITIME NEUTRALITY CONVENTION art. 4 (“Under the terms of the preceding article, a
belligerent state is forbidden: a) To make use of neutral waters as a base of naval operations against the enemy, or
to renew or augment military supplies or the armament of its ships, or to complete the equipment of the latter;”);
HAGUE XIII art. 5 (“Belligerents are forbidden to use neutral ports and waters as a base of naval operations against
their adversaries, and in particular to erect wireless telegraphy stations or any apparatus for the purpose of
communicating with the belligerent forces on land or sea.”).
95 See, e.g., Treaty between the United States and Great Britain, art. 6, May 8, 1871, 17 STAT. 863, 865 (“A neutral
Government is bound - Secondly, not to permit or suffer either belligerent to make use of its ports or waters as the
base of naval operations against the other, or for the purpose of the renewal or augmentation of military supplies or
arms, or the recruitment of men.”). Refer to § 15.3.2.2 (Duty to Prevent Violations of Neutrality Within Its
Jurisdiction).
96 Refer to § 17.18.1 (Duty of Non-Belligerent States to Refrain From Supporting Hostilities by Non-State Armed
Groups Against Other States).
97 HAGUE XIII art. 8 (“A neutral Government is bound to employ the means at its disposal to prevent the fitting out
or arming of any vessel within its jurisdiction which it has reason to believe is intended to cruise, or engage in
hostile operations, against a Power with which that Government is at peace. It is also bound to display the same
vigilance to prevent the departure from its jurisdiction of any vessel intended to cruise, or engage in hostile
operations, which has been adapted entirely or partly within the said jurisdiction for use in war.”); Treaty between
the United States and Great Britain, art. 6, May 8, 1871, 17 STAT. 863, 865 (“A neutral Government is bound - First,
to use due diligence to prevent the fitting out, arming, or equipping, within its jurisdiction, of any vessel which it has
reasonable ground to believe is intended to cruise or to carry on war against a power with which it is at peace; and
also to use like diligence to prevent the departure from its jurisdiction of any vessel intended to cruise or carry on
war as above, such vessel having been specially adapted, in whole or in part, within such jurisdiction, to warlike
use.”).
98 1956 FM 27-10 (Change No. 1 1976) ¶526 (“It is also forbidden to permit the use of its territory for the fitting out
of hostile expeditions.”).
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replenish or increase their supplies of war materials or their armaments, or for completing their
crews.99
15.5.2 Prohibition Against Recruiting and Forming Corps of Combatants. Units of
combatants may not be formed nor may recruiting agencies be established on the territory of a
neutral State to assist a belligerent State.100 This means that the establishment of recruiting
agencies, the enlistment of personnel, the formation and organization of hostile expeditions on a
neutral State’s territory, and the passage across its frontiers of organized bodies of personnel
intending to enlist are prohibited.101
15.5.2.1 Exception for Authorized Medical Personnel. This prohibition does not
extend to medical personnel and units of voluntary aid societies of a neutral State who are duly
authorized to provide medical assistance to a belligerent State.102 In no circumstance shall such
assistance by medical personnel and units of voluntary aid societies of the neutral State be
considered as interference in the conflict.103
15.5.2.2 Exception for Persons Crossing a Neutral State’s Frontiers Separately to
Assist a Belligerent State. The prohibition against organizing units of combatants is directed
against organized bodies, which only require being armed to become an immediate fighting
force.104 Thus, the responsibility of a neutral State is not engaged by the fact of persons crossing
the frontier separately to offer their services to one of the belligerent States.105 Individuals
crossing the frontier singly or in small bands that are unorganized create no obligation on the
neutral State.106
99 HAGUE XIII art. 18 (“Belligerent war-ships may not make use of neutral ports, roadsteads, or territorial waters for
replenishing or increasing their supplies of war material or their armament, or for completing their crews.”).
100 HAGUE V art. 4 (“Corps of combatants cannot be formed nor recruiting agencies opened on the territory of a
neutral Power to assist the belligerents.”).
101 1956 FM 27-10 (Change No. 1 1976) ¶522b (“Application of Rule. The establishment of recruiting agencies, the
enlistment of men, the formation and organization of hostile expeditions on neutral territory, and the passage across
its frontiers of organized bodies of men intending to enlist are prohibited.”); Consultative Meeting of Foreign
Ministers of the American Republics, Final Act of the Meeting: V General Declaration of Neutrality of the
American Republics, ¶3, Oct. 3, 1939, 1 DEPARTMENT OF STATE BULLETIN 326, 327 (Oct. 7, 1939) (The American
Republics resolve “[t]o declare that with regard to their status as neutrals, there exist certain standards recognized by
the American Republics applicable in these circumstances and that in accordance with them they: ... (c) Shall
prevent on their respective territories the enlistment of persons to serve in the military, naval, or air forces of the
belligerents;”).
102 1956 FM 27-10 (Change No. 1 1976) ¶522c (“This prohibition does not extend to medical personnel and units of
a voluntary aid society duly authorized to join one of the belligerents. (See GWS, art. 27; par. 229 herein.)”).
103 Refer to § 4.12 (Staff of a Recognized Aid Society of a Neutral Country).
104 1956 FM 27-10 (Change No. 1 1976) ¶524a (“The prohibition in Article 4, H. V (par. 522), is directed against
organized bodies which only require to be armed to become an immediate fighting force.”).
105 HAGUE V art. 6 (“The responsibility of a neutral Power is not engaged by the fact of persons crossing the frontier
separately to offer their services to one of the belligerents.”).
106 1956 FM 27-10 (Change No. 1 1976) ¶524a (“Individuals crossing the frontier singly or in small bands that are
unorganized create no obligation on the neutral State.”).
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Neutral States shall not oppose the voluntary departure of nationals of belligerent States
even though they leave simultaneously in great numbers; but they may oppose the voluntary
departure of their own nationals going to enlist in the armed forces of belligerent States.107
Neutral States are not required to enact legislation forbidding their nationals to join the armed
forces of belligerent States.108
Neutral States, however, may not send regularly constituted military units across the
frontier in the guise of “volunteers” or small unorganized bands.109
15.5.3 Prohibition Against Establishment or Use of Belligerent Communications
Facilities in Neutral Territory. Belligerent States are prohibited from erecting on the territory of
a neutral State any apparatus for the purpose of communicating with belligerent forces on land or
sea.110 Belligerent States are prohibited from using any installation of this kind established by
them before the armed conflict on the territory of a neutral State for purely military purposes,
and which has not been opened for the service of public messages.111
15.5.3.1 Use of Neutral Facilities by Belligerents Not Prohibited. A neutral State
does not, however, have to forbid or restrict the use on behalf of belligerent States of
communications equipment and facilities belonging to the neutral State, or belonging to
companies or private individuals.112
That a neutral State, if it so desires, may transmit messages by means of its
communications facilities does not imply that the neutral State may use such facilities or permit
107 1928 PAN AMERICAN MARITIME NEUTRALITY CONVENTION art. 23 (“Neutral states shall not oppose the voluntary
departure of nationals of belligerent States even though they leave simultaneously in great numbers; but they may
oppose the voluntary departure of their own nationals going to enlist in the armed forces.”).
108 1956 FM 27-10 (Change No. 1 1976) ¶524a (“Neutral States are not required to enact legislation forbidding their
nationals to join the armed forces of the belligerents.”).
109 1956 FM 27-10 (Change No. 1 1976) ¶524a (“The foregoing rules do not, however, permit a State professing to
be neutral to send regularly constituted military units across the frontier in the guise of ‘volunteers’ or small
unorganized bands.”).
110 HAGUE V art. 3 (“Belligerents are likewise forbidden to: (a.) Erect on the territory of a neutral Power a wireless
telegraphy station or other apparatus for the purpose of communicating with belligerent forces on land or sea;”);
HAGUE XIII art. 5 (“Belligerents are forbidden to use neutral ports and waters as a base of naval operations against
their adversaries, and in particular to erect wireless telegraphy stations or any apparatus for the purpose of
communicating with the belligerent forces on land or sea.”); 1928 PAN AMERICAN MARITIME NEUTRALITY
CONVENTION art. 4 (“Under the terms of the preceding article, a belligerent state is forbidden: … b) To install in
neutral waters radio-telegraph stations or any other apparatus which may serve as a means of communication with
its military forces, or to make use of installations of this kind it may have established before the war and which may
not have been opened to the public.”).
111 HAGUE V art. 3 (“Belligerents are likewise forbidden to: ... (b.) Use any installation of this kind established by
them before the war on the territory of a neutral Power for purely military purposes, and which has not been opened
for the service of public messages.”).
112 HAGUE V art. 8 (“A neutral Power is not called upon to forbid or restrict the use on behalf of the belligerents of
telegraph or telephone cables or of wireless telegraphy apparatus belonging to it or to companies or private
individuals.”).
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their use to lend assistance to the belligerents on one side only.113 Every measure of restriction
or prohibition taken by a neutral State in regard to the use of its communications facilities and
equipment must be impartially applied by it to all belligerent States.114 It also must see to the
same obligation being observed by companies or private individuals owning such
communication equipment and facilities.115
15.5.4 Movement of Belligerent Forces and Convoys of Supplies Through Neutral Land
Territory. Belligerent States are forbidden to move forces or convoys of either munitions of war
or supplies across the land territory of a neutral State.116 This rule only prohibits the official acts
of a belligerent State in convoying or shipping munitions and supplies through a neutral State as
part of an expedition; it does not prohibit the shipment of such supplies by private persons.117
However, a neutral State may authorize passage through its territory of the wounded and
sick, including the overflight of its territory by certain medical aircraft.118
15.6 NEUTRAL PERSONS
15.6.1 Definition of Neutral Person. The nationals of a State that is not taking part in the
war are considered neutral persons.119
15.6.2 Forfeiture of Protections of Neutral Status by a Neutral Person. A national of a
neutral State would not retain the protections that a person would derive by virtue of the neutral
status of his or her State of nationality if that person commits:
• hostile acts against a belligerent State; or
• acts in favor of a belligerent State, particularly if that person voluntarily enlists in the
ranks of the armed forces of one of the parties to the armed conflict.120
113 1956 FM 27-10 (Change No. 1 1976) ¶530 (“The liberty of a neutral State, if it so desires, to transmit messages
by means of its telegraph, telephone, cable, radio, or other communications facilities does not imply the power so to
use them or to permit their use as to lend assistance to the belligerents on one side only.”).
114 HAGUE V art. 9 (“Every measure of restriction or prohibition taken by a neutral Power in regard to the matters
referred to in Articles 7 and 8 must be impartially applied by it to both belligerents.”).
115 HAGUE V art. 9 (“A neutral Power must see to the same obligations being observed by companies or private
individuals owning telegraph or telephone cables or wireless telegraphy apparatus.”).
116 HAGUE V art. 2 (“Belligerents are forbidden to move troops or convoys of either munitions of war or supplies
across the territory of a neutral Power.”).
117 1956 FM 27-10 (Change No. 1 1976) ¶517 (“A distinction must be drawn between the official acts of the
belligerent State in convoying or shipping munitions and supplies through neutral territory as part of an expedition
and the shipment of such supplies by private persons. The former is forbidden while the latter is not.”).
118 Refer to § 15.18 (Authorized Passage of Wounded and Sick Combatants Through Neutral Territory).
119 HAGUE V art. 16 (“The nationals of a State which is not taking part in the war are considered as neutrals.”).
120 HAGUE V art. 17 (“A neutral cannot avail himself of his neutrality: (a.) If he commits hostile acts against a
belligerent; (b.) If he commits acts in favor of a belligerent, particularly if he voluntarily enlists in the ranks of the
armed force of one of the parties.”).
950
For example, neutral persons who materially support one belligerent generally forfeit
their neutral character or assume certain liabilities with respect to the other belligerent.121
15.6.2.1 No More Severe Treatment Than Nationals of an Opposing Belligerent
State. A neutral person, however, shall not be more severely treated by the belligerent State as
against whom that person has abandoned his or her neutrality than a national of the other
belligerent State could be for the same act.122
Although a neutral person who takes certain actions may be liable to treatment as an
unprivileged belligerent, the forfeiture of neutral protections does not necessarily result in that
person being regarded as an unprivileged belligerent.
For example, if a national of a neutral State is a member of the armed forces of a
belligerent State, that person would be entitled to all the protections that a member of the armed
forces of the belligerent State would enjoy under the law of war, such as POW status if that
person falls into the power of the enemy during international armed conflict.123
15.6.2.2 Acts Not Considered in Favor of a Belligerent That Would Forfeit
Protections of Neutral Status. The followings acts would not be considered as committed in
favor of a belligerent State that would forfeit a neutral person’s protections of neutral status:
• furnishing supplies or making loans to a belligerent State, provided that the person who
furnishes the supplies or who makes the loans lives neither in the territory of the
belligerent State nor in the territory occupied by it, and that the supplies do not come
from these territories; or
• rendering services in matters of police or civil administration.124
In addition, merely expressing sympathy for a belligerent’s cause would not cause a
person to forfeit one’s neutral character, although incitement or recruitment would be treated
differently.
121 See also LAUTERPACHT, II OPPENHEIM’S INTERNATIONAL LAW 656 (§296) (“International Law is primarily a law
between States. For this reason the rights and duties of neutrality are principally those of neutral States as such. …
At the same time, International Law renders unlawful certain activities of nationals of neutral States, like carriage of
contraband or breach of blockade, without, however, imposing upon these States the duty to prevent or penalise such
acts. These are punished by the belligerent against whom they are directed.”); GREENSPAN, THE MODERN LAW OF
LAND WARFARE 571 (“A neutral subject who indulges in partisan activity in favor of a belligerent usually loses the
benefit of his neutral character in relation to the belligerent on the other side, as will be seen shortly. Therefore,
while a neutral person is free to assist a belligerent, he generally does so at his own risk.”).
122 HAGUE V art. 17 (“In such a case, the neutral shall not be more severely treated by the belligerent as against
whom he has abandoned his neutrality than a national of the other belligerent State could be for the same act.”).
123 Refer to § 4.4.4.1 (Nationals of Neutral States in Enemy Forces).
124 HAGUE V art. 18 (“The following acts shall not be considered as committed in favour of one belligerent in the
sense of Article 17, letter (b):
(a.) Supplies furnished or loans made to one of the belligerents, provided that the
person who furnishes the supplies or who makes the loans lives neither in the territory of the other party nor in the
territory occupied by him, and that the supplies do not come from these territories; (b.) Services rendered in matters
of police or civil administration.”).
951
Certain types of humanitarian assistance under the 1949 Geneva Conventions would also
not be regarded as a violation of neutrality by the persons engaging in those activities.125
15.6.3 Neutral Persons in the Home Territory of a Belligerent. Neutral persons in the
home territory of a belligerent State are not “protected persons” under the GC while their State of
nationality has normal diplomatic relations with the belligerent State.126
In general, neutral persons residing permanently in the territory of a belligerent State,
whether protected persons or not, are to a great extent regarded, both by that belligerent and the
opposing side, like other residents of that territory, so long as they remain there.127 By contrast,
the neutral person who is a transient visitor in the territory of a belligerent is provided particular
respect, so far as the hazards of war permit, and provided that the person’s actions are consistent
with that person’s neutral character.128
15.6.4 Neutral Persons Resident in Occupied Territory. Neutral persons resident in
occupied territory are not entitled to claim different treatment, in general, from that accorded the
other inhabitants.129 They must refrain from all participation in the war and from all hostile acts,
and must observe strictly the rules of the Occupying Power.130
All nationals of neutral States, whether resident in or temporarily visiting an occupied
territory, may be punished for offenses committed by them to the same extent and in the same
manner as enemy nationals.131 In addition, it may be possible to extradite nationals of neutral
States who have committed offenses to their home States for prosecution. If nationals of neutral
States are not “protected persons,” they may be deported or expelled for just cause.132
125 Refer to § 4.12 (Staff of a Recognized Aid Society of a Neutral Country); § 7.12.1.3 (Authorized Neutral Civilian
Hospital Ships).
126 Refer to § 10.3.3.3 (Nationals of a Neutral State or Co-Belligerent State While Normal Diplomatic
Representation Exists).
127 GREENSPAN, THE MODERN LAW OF LAND WARFARE 575 (“In general, neutrals residing permanently in the
territory of a belligerent, whether protected persons or not, are to a great extent regarded, both by that belligerent
and the opposing side, as sharing the lot and character of the people among whom they reside, so long as they
continue there.”).
128 GREENSPAN, THE MODERN LAW OF LAND WARFARE 577-78 (“The neutral who is merely a transient visitor in the
territory of a belligerent falls into a different category from the resident neutral; provided, of course, that his actions
are consistent with his neutral character. Both his person and his property are entitled to particular respect from the
belligerents, so far as the hazards of war permit.”).
129 1956 FM 27-10 (Change No. 1 1976) ¶548 (“Neutral persons resident in occupied territory are not entitled to
claim different treatment, in general, from that accorded the other inhabitants.”).
130 1956 FM 27-10 (Change No. 1 1976) ¶548 (“They must refrain from all participation in the war, from all hostile
acts, and observe strictly the rules of the occupant.”).
131 1956 FM 27-10 (Change No. 1 1976) ¶550 (“All nationals of neutral powers, whether resident or temporarily
visiting an occupied territory, may be punished for offenses committed by them to the same extent and in the same
manner as enemy nationals.”).
132 1958 UK MANUAL ¶691 note 1 (“If such neutrals are not ‘protected persons’ then they may be expelled or
deported for just cause by the military or civil authorities of the Occupant.”).
952
In the event that such a person is arrested, suspicions must be verified by a serious
inquiry, and the arrested neutral person must be given an opportunity to present a defense, and to
communicate with his or her national consul if requested.133 In addition, the minimum standards
for humane treatment and for detention procedures would be applicable.134
15.6.4.1 Protected Person Status of Neutral Persons in Occupied Territory.
Neutral persons, among other persons, who find themselves in the hands of an Occupying Power
generally would be regarded as “protected persons” under the GC.135 Neutral persons who travel
to occupied territory for the purpose of fighting the Occupying Power are not regarded as
“protected persons” under the GC.136
15.6.4.2 Diplomatic Agents and Consular Personnel in Occupied Territory.
Diplomatic agents of neutral States must be treated with all courtesy and must be permitted such
freedom of action as it is possible to allow, with due regard to the necessities of the war. The
same is true of consular personnel of neutral States, except those who are enemy nationals.137
133 In the Matter of the Claim of Madame Chevreau Against the United Kingdom, Arbitral Award, reprinted in 27
AJIL 153, 160 (1933) (“The principles involved in the present case which, among others, have been applied by
different international commissions, may be briefly stated as follows: (1) The arbitrary arrest, detention or
deportation of a foreigner may give rise to a claim in international law. But the claim is not justified if these
measures were taken in good faith and upon reasonable suspicion, especially if a zone of military operations is
involved. (2) In cases of arrest, suspicions must be verified by a serious inquiry, and the arrested person given an
opportunity to defend himself against the suspicions directed against him, and particularly to communicate with the
consul of his country if he requests it. If there is no inquiry, or if it is unnecessarily delayed, or, in general, if the
detention is unnecessarily prolonged, there is ground for a claim.”).
134 Refer to § 8.2 (Humane Treatment of Detainees); § 8.14 (Procedures for Detention).
135 See Jack L. Goldsmith III, Assistant Attorney General, “Protected Person” Status in Occupied Iraq Under the
Fourth Geneva Convention, Mar. 18, 2004, 28 OPINIONS OF THE OFFICE OF LEGAL COUNSEL 35, 45 (“Second,
‘territory of a belligerent State’ might refer to the home territory of the party to the conflict in whose hands the
citizen of the neutral State finds himself. As applied to the armed conflict with Iraq, this interpretation would deny
‘protected person[]’ status to citizens of neutral States who find themselves in the territory of the United States, but
not to those who find themselves in occupied Iraq. We conclude that the second interpretation is correct.”)
(amendment in original). See also II-A FINAL RECORD OF THE DIPLOMATIC CONFERENCE OF GENEVA OF 1949 793
(“A particularly delicate question was that of the position of the nationals of neutral States. The Drafting Committee
had made a distinction between the position of neutrals in the home territory of belligerents and that of neutrals in
occupied territory. In the former case, neutrals were protected by normal diplomatic representation; in the latter
case, on the other hand, the diplomatic representatives concerned were only accredited to the Government of the
occupied States, whereas authority rested with the Occupying Power. It followed that all neutrals in occupied
territory must enjoy protection under the Convention, while neutrals in the home territory of a belligerent only
required such protection if the State whose nationals they were had no normal diplomatic representation in the
territory in question. The text drawn up by the Drafting Committee had taken account of the above
considerations.”).
136 Refer to § 10.3.2.1 (“Find Themselves”).
137 1956 FM 27-10 (Change No. 1 1976) ¶549 (“Diplomatic agents of neutral States must be treated with all courtesy
and must be permitted such freedom of action as it is possible to allow, with due regard to the necessities of the war.
The same is true of consular personnel of neutral States, except those who are enemy nationals.”).
953
15.7 NEUTRAL WATERS
Belligerent States are forbidden to use a neutral State’s ports and waters as a base of
naval operations against their adversaries, and in particular to erect or employ any apparatus for
communicating with belligerent forces on land or sea.138 For example, a belligerent State’s
warships may not make use of a neutral State’s ports, roadsteads, and territorial waters to
replenish or increase their supplies of war materials or their armaments, or for completing their
crews.139
Belligerent State forces must refrain from acts of hostility in neutral waters, including the
exercise of visit and search.140
The neutral State has an affirmative duty to police its waters to prevent violations of
neutrality in its waters.141 If a neutral State is unable or unwilling to detect and expel belligerent
forces unlawfully present in its waters, the opposing belligerent State may undertake such self-
help enforcement actions as may be necessary to terminate the violation of neutrality.
15.7.1 Waters That Are Considered Neutral. The waters that are subject to the
sovereignty of a neutral State are considered neutral. Neutral waters may be understood to
include the following waters belonging to a neutral State:
• the territorial sea, including up to 12 nautical miles;142
• archipelagic waters;143 and
• ports, roadsteads, and internal waters.144
For the purpose of applying the law of neutrality, all ocean areas not subject to the
territorial sovereignty of any State (i.e., all waters seaward of neutral States’ territorial seas) are
not considered neutral waters. The following waters are not considered neutral waters:
• a neutral State’s contiguous zone;145
138 HAGUE XIII art. 5 (“Belligerents are forbidden to use neutral ports and waters as a base of naval operations
against their adversaries, and in particular to erect wireless telegraphy stations or any apparatus for the purpose of
communicating with the belligerent forces on land or sea.”).
139 HAGUE XIII art. 18 (“Belligerent war-ships may not make use of neutral ports, roadsteads, or territorial waters for
replenishing or increasing their supplies of war material or their armament, or for completing their crews.”).
140 Refer to § 15.13.3 (Where Belligerents May Not Exercise the Right of Visit and Search).
141 Hague XIII art. 25 (“A neutral Power is bound to exercise such surveillance as the means at its disposal allow to
prevent any violation of the provisions of the above Articles occurring in its ports or roadsteads or in its waters.”).
142 Refer to § 13.2.2.2 (Territorial Seas).
143 Refer to § 13.2.2.3 (Archipelagic Waters).
144 Refer to § 13.2.2.1 (Internal Waters).
145 Refer to § 13.2.3.2 (Contiguous Zones).
954
• a neutral State’s exclusive economic zone;146 and
• the high seas.147
15.7.2 A Neutral State’s Regulations Concerning Belligerent Warships and Prizes in Its
Waters. A neutral State may adopt laws or regulations governing the presence of belligerent
warships and their prizes in its waters.
A neutral State must apply impartially to opposing belligerents the conditions,
restrictions, or prohibitions made by the neutral State in regard to the admission into its ports,
roadsteads, or territorial waters, of belligerent warships or of their prizes.148 Nevertheless, a
neutral Power may forbid a belligerent vessel that has failed to conform to the orders and
regulations made by it, or that has violated neutrality, to enter its ports or roadsteads.149
15.7.3 24-Hour Limit on Stay of Belligerent Warships in Neutral Waters. In the absence
of special provisions to the contrary in the legislation of a neutral State, a belligerent State’s
warships are generally prohibited from remaining in that neutral State’s ports, roadsteads, or
territorial waters for more than 24 hours.150
A belligerent warship may not prolong its stay in a neutral port beyond the permissible
time except on account of damage or stress of weather. It must depart as soon as the cause of the
delay is at an end.151
The regulations as to the question of the length of time that these vessels may remain in
neutral ports, roadsteads, or waters, do not apply to warships devoted exclusively to religious,
146 Refer to § 13.2.3.3 (Exclusive Economic Zones (EEZs)).
147 Refer to § 13.2.3.4 (High Seas).
148 HAGUE XIII art. 9 (“A neutral Power must apply impartially to the two belligerents the conditions, restrictions, or
prohibitions made by it in regard to the admission into its ports, roadsteads, or territorial waters, of belligerent war-
ships or of their prizes.”).
149 HAGUE XIII art. 9 (“Nevertheless, a neutral Power may forbid a belligerent vessel which has failed to conform to
the orders and regulations made by it, or which has violated neutrality, to enter its ports or roadsteads.”).
150 HAGUE XIII art. 12 (“In the absence of special provisions to the contrary in the legislation of a neutral Power,
belligerent war-ships are not permitted to remain in the ports, roadsteads, or territorial waters of the said Power for
more than twenty-four hours, except in cases covered by the present Convention.”); 1928 PAN AMERICAN
NEUTRALITY CONVENTION art. 5 (“Belligerent warships are forbidden to remain in the ports or waters of a neutral
state more than twenty-four hours. This provision will be communicated to the ship as soon as it arrives in port or in
the territorial waters, and if already there at the time of the declaration of war, as soon as the neutral state becomes
aware of this declaration.”).
151 HAGUE XIII art. 14 (“A belligerent war-ship may not prolong its stay in a neutral port beyond the permissible
time except on account of damage or stress of weather. It must depart as soon as the cause of the delay is at an
end.”). See also 1928 PAN AMERICAN NEUTRALITY CONVENTION art. 5 (“A ship may extend its stay in port more
than twenty-four hours in case of damage or bad conditions at sea, but must depart as soon as the cause of the delay
has ceased. When, according to the domestic law of the neutral state, the ship may not receive fuel until twenty-four
hours after its arrival in port, the period of its stay may be extended an equal length of time.”).
955
scientific, or philanthropic purposes.152 Warships engaged in the collection of scientific data of
potential military application would not be considered to be devoted exclusively to scientific
purposes and would not be exempt.153
15.7.3.1 Notification to Belligerent Warships to Depart a Neutral State’s Waters
Upon Outbreak of Hostilities. If a neutral State, which has been informed of the outbreak of
hostilities, learns that a belligerent State’s warship is in one of the neutral State’s ports or
roadsteads, or in its territorial waters, it must notify such warship to depart within 24 hours or
within the time prescribed by local regulations.154
15.7.4 Passage of Belligerent Warships and Prizes Through a Neutral State’s Waters. A
neutral State may allow the passage of belligerent warships and prizes through its waters. The
neutrality of a State is not affected by the mere passage through its territorial waters of warships
or prizes belonging to belligerents.155
A neutral State may, on a nondiscriminatory basis, suspend passage of belligerent
warships and prizes through its waters (with the exception of international straits and
archipelagic sea lanes).156
Although the general practice has been to close neutral territorial seas to belligerent
submarines, a neutral State may elect to allow passage of submarines provided they do not
engage in hostile acts while in territorial waters.157
Neutral States customarily authorize passage through their territorial sea of ships carrying
the wounded, sick, and shipwrecked, whether or not those waters are otherwise closed to
belligerent vessels.158
152 HAGUE XIII art. 14 (“The regulations as to the question of the length of time which these vessels may remain in
neutral ports, roadsteads, or waters, do not apply to war-ships devoted exclusively to religious, scientific, or
philanthropic purposes.”); 1928 PAN AMERICAN MARITIME NEUTRALITY CONVENTION art. 5 (“Vessels used
exclusively for scientific, religious, or philanthropic purposes are exempted from the foregoing provisions.”).
153 2007 NWP 1-14M ¶7.3.2.1 (“Warships engaged in the collection of scientific data of potential military
application are not exempt.”); 1997 NWP 9 ¶7.3.2.1 (same); 1989 NWP 9 ¶7.3.2.1 (“Vessels engaged in the
collection of scientific data of potential military application are not exempt”).
154 HAGUE XIII art. 13 (“If a Power which has been informed of the outbreak of hostilities learns that a belligerent
war-ship is in one of its ports or roadsteads, or in its territorial waters, it must notify the said ship to depart within
twenty-four hours or within the time prescribed by local regulations.”).
155 HAGUE XIII art. 10 (“The neutrality of a Power is not affected by the mere passage through its territorial waters
of war-ships or prizes belonging to belligerents.”).
156 2007 NWP 1-14M ¶7.3.4 (“A neutral nation may, on a nondiscriminatory basis, suspend passage of belligerent
warships and prizes through its territorial seas, except in international straits.”); 1997 NWP 9 ¶7.3.4 (same); 1989
NWP 9 ¶7.3.4.1 (“A neutral nation may, on a nondiscriminatory basis, close its territorial waters, except in
international straits, to belligerent vessels.”).
157 2007 NWP 1-14M ¶7.3.4 (“Although the general practice has been to close neutral territorial seas to belligerent
submarines, a neutral nation may elect to allow passage of submarines.”); 1997 NWP 9 ¶7.3.4 (same); 1989 NWP 9
¶7.3.4.1 (“Although the general practice has been to close neutral territorial waters to belligerent submarines, a
neutral nation may elect to allow passage of submarines, either surfaced or submerged.”).
956
15.7.4.1 Right of Entry in Distress for Belligerent Vessels. Belligerent vessels,
including warships, have a right of entry in distress whether caused by force majeure or damage
resulting from enemy action.159 The right of entry in distress does not prejudice the measures
that a neutral State may take after entry has been granted, such as measures to intern the ship if it
remains when it is not entitled to remain.160
15.8 PASSAGE OF BELLIGERENT VESSELS AND AIRCRAFT THROUGH INTERNATIONAL STRAITS AND
ARCHIPELAGIC SEA LANES
Although a neutral State may suspend the passage of belligerent warships through its
waters, a neutral State may not suspend, hamper, or otherwise impede the access of belligerent
vessels and aircraft through international straits overlapped by neutral waters or archipelagic sea
lanes of a neutral State.
Belligerent vessels and aircraft transiting through international straits overlapped by
neutral waters or archipelagic sea lanes of a neutral State must adhere to certain requirements.
15.8.1 Passage of Belligerent Vessels and Aircraft Through International Straits
Overlapped by Neutral Waters. All ships and aircraft (including those belonging to belligerent
and neutral States) have a right of transit passage through, over, and under all straits used for
international navigation.161 Such passage by vessels carrying contraband of war or by belligerent
warships is not regarded as compromising the neutrality of the State with water overlapping such
straits.162 Neutral States bordering international straits may not suspend, hamper, or otherwise
impede the right of transit passage through international straits.163
158 2007 NWP 1-14M ¶7.3.4 (“Neutral nations customarily authorize passage through their territorial sea of ships
carrying the wounded, sick, and shipwrecked, whether or not those waters are otherwise closed to belligerent
vessels.”); 1997 NWP 9 ¶7.3.4 (same); 1989 NWP 9 ¶7.3.4.1 (same).
159 TUCKER, THE LAW OF WAR AND NEUTRALITY AT SEA 240 (“It is generally recognized, however, that
international practice requires that exception be made in the neutrality regulations of states to permit the entry of
belligerent warships in distress. Entry in distress may result from weather or sea conditions, but it may also result
from damage incurred in battle. Even pursuit by the enemy appears to give belligerent warships a right of entry.
But this right of entry in distress cannot be held to prejudice the measures a neutral state may take once admission
into its waters and ports has been granted.”).
160 Refer to § 15.9.2 (Detention of Belligerent Ships That, and Personnel Who, Are Not Entitled to Remain in a
Neutral Port).
161 See 2007 NWP 1-14M ¶7.3.6 (“Customary international law as reflected in the 1982 LOS Convention provides
that belligerent and neutral surface ships, submarines, and aircraft have a right of transit passage through, over, and
under all straits used for international navigation.”). Consider LOS CONVENTION art. 38(1) (“In straits referred to in
article 37 [i.e., straits that are used for international navigation between one part of the high seas or an exclusive
economic zone and another part of the high seas or an exclusive economic zone], all ships and aircraft enjoy the
right of transit passage, which shall not be impeded.”).
162 The S.S. Wimbledon, (United Kingdom, France, Japan v. Germany) (Judgment), 1923 P.C.I.J. (series A) No. 1,
at 28 (“The precedents therefore afforded by the Suez and Panama Canals invalidate in advance the argument that
Germany's neutrality would have necessarily been imperilled [sic] if her authorities had allowed the passage of the
‘Wimbledon’ through the Kiel Canal, because that vessel was carrying contraband of war consigned to a state then
engaged in an armed conflict. Moreover they are merely illustrations of the general opinion according to which
when an artificial waterway connecting two open seas has been permanently dedicated to the use of the whole
957
Belligerent forces transiting through international straits overlapped by neutral waters
must proceed without delay, must refrain from the threat or use of force against the neutral State,
and must otherwise refrain from acts of hostility and other activities not incident to their
transit.164 For example, belligerent forces must refrain from exercising the right of visit and
search while transiting through international straits that are overlapped by neutral waters.165
Belligerent forces in transit may, however, take defensive measures consistent with their
security, including the launching and recovery of military devices, screen formation steaming,
and acoustic and electronic surveillance, and may respond in self-defense to a hostile act or a
demonstration of hostile intent.166
15.8.2 Passage of Belligerent Vessels and Aircraft Through Archipelagic Sea Lanes of a
Neutral State. Belligerent ships or aircraft, including surface warships, submarines, and military
aircraft, retain the right of unimpeded archipelagic sea167 lanes passage through, under, and over
neutral archipelagic sea lanes.168 Neutral archipelagic States shall not suspend or hamper the
right of transit passage through their archipelagic sea lanes.169
world, such waterway is assimilated to natural straits in the sense that even the passage of a belligerent man-of-war
does not compromise the neutrality of the sovereign State under whose jurisdiction the waters in question lie.”).
163 2007 NWP 1-14M ¶7.3.6 (“Neutral nations cannot suspend, hamper, or otherwise impede this right of transit
passage through international straits.”). Consider LOS CONVENTION art. 44 (“States bordering straits shall not
hamper transit passage and shall give appropriate publicity to any danger to navigation or overflight within or over
the strait of which they have knowledge. There shall be no suspension of transit passage.”).
164 2007 NWP 1-14M ¶7.3.6 (“Belligerent forces transiting through international straits overlapped by neutral waters
must proceed without delay, must refrain from the threat or use of force against the neutral nation, and must
otherwise refrain from acts of hostility and other activities not incident to their transit.”). Consider LOS
CONVENTION art. 39(1) (“Ships and aircraft, while exercising the right of transit passage, shall: (a) proceed without
delay through or over the strait; (b) refrain from any threat or use of force against the sovereignty, territorial
integrity or political independence of States bordering the strait, or in any other manner in violation of the principles
of international law embodied in the Charter of the United Nations; (c) refrain from any activities other than those
incident to their normal modes of continuous and expeditious transit unless rendered necessary by force majeure or
by distress.”).
165 Refer to § 15.13.3 (Where Belligerents May Not Exercise the Right of Visit and Search).
166 2007 NWP 1-14M ¶7.3.6 (“Belligerent forces in transit may, however, take defensive measures consistent with
their security, including the launching and recovery of military devices, screen formation steaming, and acoustic and
electronic surveillance, and may respond in self-defense to a hostile act or hostile intent.”).
167 Refer to § 13.2.2.3 (Archipelagic Waters).
168 2007 NWP 1-14M ¶7.3.7 (“Belligerent ships or aircraft, including surface warships, submarines and military
aircraft, retain the right of unimpeded archipelagic sea lanes passage through, under, and over neutral archipelagic
sea lanes.”). Consider LOS CONVENTION art. 53(2) (“All ships and aircraft enjoy the right of archipelagic sea lanes
passage in such sea lanes and air routes.”).
169 Consider LOS CONVENTION art. 54 (“Articles 39, 40, 42 and 44 apply mutatis mutandis to archipelagic sea lanes
passage.”); LOS CONVENTION art. 44 (“States bordering straits shall not hamper transit passage and shall give
appropriate publicity to any danger to navigation or overflight within or over the strait of which they have
knowledge. There shall be no suspension of transit passage.”).
958
Belligerent State forces exercising the right of archipelagic sea lanes passage must refrain
from acts of hostility and other activities not incident to their transit.170 For example, belligerent
State forces must refrain from exercising the right of visit and search while exercising the right
of archipelagic sea lanes passage.171 Belligerent State forces exercising the right of archipelagic
sea lanes passage may, however, engage in those activities that are incident to their normal mode
of continuous and expeditious passage, and that are consistent with their security, including
formation steaming, acoustic and electronic surveillance, and the launching and recovery of
military devices.172
15.9 ADDITIONAL RULES APPLICABLE TO NEUTRAL PORTS, ROADSTEADS, AND INTERNAL
WATERS
In addition to the general rules applicable to neutral waters,173 certain other rules apply to
neutral ports, roadsteads, and internal waters.
15.9.1 Maximum Number of Belligerent Warships in One Neutral Port or Roadstead. In
the absence of special provisions to the contrary in the legislation of a neutral State, the
maximum number of warships belonging to a belligerent that may be in one of the ports or
roadsteads of that neutral State simultaneously is three.174
170 Consider LOS CONVENTION art. 54 (“Articles 39, 40, 42 and 44 apply mutatis mutandis to archipelagic sea lanes
passage.”); LOS CONVENTION art. 39 (“Ships and aircraft, while exercising the right of transit passage, shall: (a)
proceed without delay through or over the strait; (b) refrain from any threat or use of force against the sovereignty,
territorial integrity or political independence of States bordering the strait, or in any other manner in violation of the
principles of international law embodied in the Charter of the United Nations; (c) refrain from any activities other
than those incident to their normal modes of continuous and expeditious transit unless rendered necessary by force
majeure or by distress.”).
171 Refer to § 15.13.3 (Where Belligerents May Not Exercise the Right of Visit and Search).
172 2007 NWP 1-14M ¶7.3.7 (“Belligerent forces exercising the right of archipelagic sea lanes passage may engage
in those activities that are incident to their normal mode of continuous and expeditious passage and are consistent
with their security, including formation steaming, acoustic and electronic surveillance, and the launching and
recovery of military devices.”). Consider LOS CONVENTION art. 53(3) (“Archipelagic sea lanes passage means the
exercise in accordance with this Convention of the rights of navigation and overflight in the normal mode solely for
the purpose of continuous, expeditious and unobstructed transit between one part of the high seas or an exclusive
economic zone and another part of the high seas or an exclusive economic zone.”).
173 Refer to § 15.7 (Neutral Waters).
174 See Consultative Meeting of Foreign Ministers of the American Republics, Final Act of the Meeting: V General
Declaration of Neutrality of the American Republics, ¶3, Oct. 3, 1939, 1 DEPARTMENT OF STATE BULLETIN 326, 327
(Oct. 7, 1939) (The American Republics resolve “[t]o declare that with regard to their status as neutrals, there exist
certain standards recognized by the American Republics applicable in these circumstances and that in accordance
with them they: ... (d) May determine, with regard to belligerent warships, that not more than three at a time be
admitted in their own ports or waters and in any case they shall not be allowed to remain for more than twenty-four
hours. Vessels engaged exclusively in scientific, religious or philanthropic missions may be exempted from this
provision, as well as those which arrive in distress.”); 1928 PAN AMERICAN NEUTRALITY CONVENTION art. 7 (“In the
absence of a special provision of the local legislation, the maximum number of ships of war of a belligerent which
may be in a neutral port at the same time shall be three.”); HAGUE XIII art. 15 (“In the absence of special provisions
to the contrary in the legislation of a neutral Power, the maximum number of war-ships belonging to a belligerent
which may be in one of the ports or roadsteads of that Power simultaneously shall be three.”).
959
15.9.2 Detention of Belligerent Ships That, and Personnel Who, Are Not Entitled to
Remain in a Neutral Port. If, notwithstanding the notification of the neutral State, a belligerent
ship of war does not leave a port where it is not entitled to remain, the neutral State is entitled to
take such measures as it considers necessary to render the ship incapable of taking to sea during
the war, and the commanding officer of the ship must facilitate the execution of such
measures.175
When a belligerent ship is detained by a neutral Power, the officers and crew are likewise
detained.176
The officers and crew thus detained may be left in the ship or kept either on another
vessel or on land, and may be subjected to the measures of restriction that may appear necessary
to impose upon them. A sufficient number of persons for looking after the vessel must, however,
always be left on board. The officers may be left at liberty on giving their word not to quit the
neutral territory without permission.177
15.9.3 Departure of Belligerent Warships in Relation to the Departure of Ships of the
Opposing Belligerent. When warships of opposing belligerent States are present simultaneously
in a neutral State’s port or roadstead, a period of not less than 24 hours must elapse between the
departure of the respective enemy warships.178 The order of departure is determined by the order
of arrival, unless the ship that arrived first is in such circumstances that an extension of its stay is
permissible.179
175 HAGUE XIII art. 24 (“If, notwithstanding the notification of the neutral Power, a belligerent ship of war does not
leave a port where it is not entitled to remain, the neutral Power is entitled to take such measures as it considers
necessary to render the ship incapable of taking the sea during the war, and the commanding officer of the ship must
facilitate the execution of such measures.”); 1928 PAN AMERICAN NEUTRALITY CONVENTION art. 6 (“The ship
which does not conform to the foregoing rules may be interned by order of the neutral government. A ship shall be
considered as interned from the moment it receives notice to that effect from the local neutral authority, even though
a petition for reconsideration of the order has been interposed by the transgressing vessel, which shall remain under
custody from the moment it receives the order.”).
176 HAGUE XIII art. 24 (“When a belligerent ship is detained by a neutral Power, the officers and crew are likewise
detained.”).
177 HAGUE XIII art. 24 (“The officers and crew thus detained may be left in the ship or kept either on another vessel
or on land, and may be subjected to the measures of restriction which it may appear necessary to impose upon them.
A sufficient number of men for looking after the vessel must, however, be always left on board. The officers may
be left at liberty on giving their word not to quit the neutral territory without permission.”). Refer to § 15.16.4
(Parole of Belligerent Personnel Interned in Neutral Territory).
178 See 1928 PAN AMERICAN NEUTRALITY CONVENTION art. 8 (“A ship of war may not depart from a neutral port
within less than twenty-four hours after the departure of an enemy warship.”); HAGUE XIII art. 16 (“When war-ships
belonging to both belligerents are present simultaneously in a neutral port or roadstead, a period of not less than
twenty-four hours must elapse between the departure of the ship belonging to one belligerent and the departure of
the ship belonging to the other.”).
179 1928 PAN AMERICAN NEUTRALITY CONVENTION art. 8 (“The one entering first shall depart first, unless it is in
such condition as to warrant extending its stay.”); HAGUE XIII art. 16 (“The order of departure is determined by the
order of arrival, unless the ship which arrived first is so circumstanced that an extension of its stay is permissible.”).
960
A belligerent warship may not leave a neutral port or roadstead until 24 hours after the
departure of a merchant ship flying the flag of its adversary.180
15.9.4 Supplies and Repairs of Belligerent Warships in Neutral Ports and Roadsteads.
15.9.4.1 Food and Fuel for Belligerent Warships in Neutral Ports and
Roadsteads. A neutral State has discretion to issue and implement regulations regarding the
supply of food and supplies for belligerent warships in its territory.181 However, such
regulations must be applied impartially among belligerent States.182
A belligerent State’s warships may take on food supplies and provisions in a neutral
State’s ports and roadsteads, but only to bring up their supplies to the peacetime standard.183
Similarly, a belligerent State’s warship may only take on sufficient fuel to enable it to
reach the nearest port in its own country.184 The belligerent State’s warship may, however, fill
up its bunkers built to carry fuel when the neutral State has adopted this method of determining
the amount of fuel to be supplied.185
15.9.4.2 Repairs of Belligerent Warships in a Neutral State’s Ports and
Roadsteads. A belligerent State’s warships may only carry out such repairs in a neutral State’s
ports and roadsteads as are absolutely necessary to render the warships seaworthy; they may not
add to or repair weapons systems, or enhance any other aspect of their war fighting capability.186
The neutral State shall decide what repairs are necessary to restore seaworthiness; repairs must
be accomplished with the least possible delay.187
180 HAGUE XIII art. 16 (“A belligerent war-ship may not leave a neutral port or roadstead until twenty-four hours
after the departure of a merchant-ship flying the flag of its adversary.”).
181 1928 PAN AMERICAN MARITIME NEUTRALITY CONVENTION art. 10 (“Belligerent warships may supply
themselves with fuel and stores in neutral ports, under the conditions especially established by the local authority
and in case there are no special provisions to that effect, they may supply themselves in the manner prescribed for
provisioning in time of peace.”).
182 Refer to § 15.7.2 (A Neutral State’s Regulations Concerning Belligerent Warships and Prizes in Its Waters).
183 HAGUE XIII art. 19 (“Belligerent war-ships may only revictual in neutral ports or roadsteads to bring up their
supplies to the peace standard.”).
184 HAGUE XIII art. 19 (“Similarly these vessels may only ship sufficient fuel to enable them to reach the nearest port
in their own country.”).
185 HAGUE XIII art. 19 (“They may, on the other hand, fill up their bunkers built to carry fuel, when in neutral
countries which have adopted this method of determining the amount of fuel to be supplied.”).
186 HAGUE XIII art. 17 (“In neutral ports and roadsteads belligerent war-ships may only carry out such repairs as are
absolutely necessary to render them seaworthy, and may not add in any manner whatsoever to their fighting force.”);
1928 PAN AMERICAN MARITIME NEUTRALITY CONVENTION art. 9 (“Damaged belligerent ships shall not be
permitted to make repairs in neutral ports beyond those that are essential to the continuance of the voyage and which
in no degree constitute an increase in its military strength.”).
187 HAGUE XIII art. 17 (“The local authorities of the neutral Power shall decide what repairs are necessary, and these
must be carried out with the least possible delay.”); 1928 PAN AMERICAN MARITIME NEUTRALITY CONVENTION art.
9 (“The neutral state shall ascertain the nature of the repairs to be made and will see that they are made as rapidly as
possible.”).
961
If the 1928 Pan American Maritime Neutrality Convention is applicable, then damage
found to have been produced by the enemy’s fire must not be repaired.188 However, whether
such repairs are prohibited by customary international law is less clear.189 Some States have
allowed such repairs provided they are limited to rendering the ship sufficiently seaworthy to
continue its voyage safely.190
A belligerent warship damaged by enemy fire that will not (or cannot) be put to sea once
the lawful period of stay has expired must be interned.191
15.9.5 Prizes in Neutral Ports or Roadsteads. A prize (i.e., a captured neutral or enemy
merchant ship) may only be brought into a neutral port or roadstead because of unseaworthiness,
stress of weather, or want of fuel or provisions.192 It must leave as soon as such circumstances
that justified its entry cease.193 Neutral ports may not be used as harbors of safety in which
prizes may be kept indefinitely.194
188 1928 PAN AMERICAN MARITIME NEUTRALITY CONVENTION art. 9 (“Damages which are found to have been
produced by the enemy’s fire shall in no case be repaired.”).
189 See TUCKER, THE LAW OF WAR AND NEUTRALITY AT SEA 244-45 (“But it is more than doubtful that the law
presently forbids the repair of battle damage in neutral ports, and, in fact, some states when neutral still allow such
repairs.”).
190 For example, TUCKER, THE LAW OF WAR AND NEUTRALITY AT SEA 245 footnote 2 (“As illustrated by the
incident involving the German battleship Admiral Graf Spee. See Hackworth, op. cit., Vol. VII, pp. 450-1. On
December 13, 1939, the Graf Spee entered the Uruguayan port of Montevideo, following an engagement with
British naval forces. A request was made to the Uruguayan authorities to permit the Graf Spee to remain fifteen
days in port in order to repair damages suffered in battle and to restore the vessel's navigability. The Uruguayan
authorities granted a seventy-two hour period of stay. Shortly before the expiration of this period the Graf Spee left
Montevideo and was destroyed by its own crew in the Rio de la Plata. The British Government, while not insisting
that Article 17 of Hague XIII clearly prohibited the repair of battle damage, did point to the widespread practice of
states when neutral in forbidding the repair of battle damage in their ports. In accordance with this practice it was
suggested that the Graf Spee’s period of stay be limited to twenty-four hours. Uruguay maintained, however, that
the scope of the neutral's duty required it only to prevent those repairs that would serve to augment the fighting force
of a vessel but not repairs necessary for safety of navigation.—The incident is noteworthy as an example of the
extent to which belligerents seemingly can make use of neutral ports without violating the prohibition against using
neutral territory as a base of naval operations.”).
191 Refer to § 15.9.2 (Detention of Belligerent Ships That, and Personnel Who, Are Not Entitled to Remain in a
Neutral Port).
192 1928 PAN AMERICAN MARITIME NEUTRALITY CONVENTION art. 17 (“Prizes cannot be taken to a neutral port
except in case of unseaworthiness, stress of weather, or want of fuel or provisions.”); HAGUE XIII art. 21 (“A prize
may only be brought into a neutral port on account of unseaworthiness, stress of weather, or want of fuel or
provisions.”).
193 1928 PAN AMERICAN MARITIME NEUTRALITY CONVENTION art. 17 (“When the cause has disappeared, the prizes
must leave immediately;”); HAGUE XIII art. 21 (“It must leave as soon as the circumstances which justified its entry
are at an end.”).
194 The S.S. Appam, 243 U.S. 124, 148-49 (1917) (“It is familiar international law that the usual course after the
capture of the Appam would have been to take her into a German port, where a prize court of that nation might have
adjudicated her status, and, if it so determined, condemned the vessel as a prize of war. Instead of that, the vessel
was neither taken to a German port nor to the nearest port accessible of a neutral power, but was ordered to, and did,
proceed over a distance of more than 3,000 miles, with a view to laying up the captured ship in an American port. It
was not the purpose to bring the vessel here within the privileges universally recognized in international law -- i.e.,
962
If the prize does not leave as soon as such circumstances that justified it entry cease, the
neutral State must order the prize to leave at once, and should it fail to do so, the neutral State
must employ the means at its disposal to release it with its previous officers and crew, and to
intern the prize crew.195
If a prize is brought into a neutral State’s port under circumstances other than because of
unseaworthiness, stress of weather, or want of fuel or provisions, the neutral State must release
the prize.196 The prize crew should be interned and the vessel restored to its former crew.197
15.9.5.1 Article 23 of Hague XIII - Prizes Sequestrated Pending Prize Court
Decision. Article 23 of Hague XIII permits a neutral State to allow prizes to enter its ports and
roadsteads when they are brought there to be sequestrated pending the decision of a prize
court.198 However, the United States ratified Hague XIII subject to a reservation to Article 23.199
for necessary fuel or provisions, or because of stress of weather or necessity of repairs, and to leave as soon as the
cause of such entry was satisfied or removed. … The principles of international law recognized by this government,
leaving the treaty aside, will not permit the ports of the United States to be thus used by belligerents. If such use
were permitted, it would constitute of the ports of a neutral country harbors of safety into which prizes, captured by
one of the belligerents, might be safely brought and indefinitely kept.”).
195 HAGUE XIII art. 21 (“If it does not [leave], the neutral Power must order it to leave at once; should it fail to obey,
the neutral Power must employ the means at its disposal to release it with its officers and crew and to intern the prize
crew.”); 1928 PAN AMERICAN MARITIME NEUTRALITY CONVENTION art. 17 (“if none of the indicated conditions
exist, the state shall suggest to them that they depart, and if not obeyed shall have recourse to the means at its
disposal to disarm them with their officers and crew, or to intern the prize crew placed on board by the captor.”).
196 HAGUE XIII art. 22 (“A neutral Power must, similarly, release a prize brought into one of its ports under
circumstances other than those referred to in Article 21.”); 1928 PAN AMERICAN NEUTRALITY CONVENTION art. 18
(“Outside of the cases provided for in Article 17, the neutral state must release the prizes which may have been
brought into its territorial waters.”).
197 Press Release, Oct. 28, 1939, German Capture of the American Steamer City of Flint, 1 DEPARTMENT OF STATE
BULLETIN 429, 432 (“A prize crew may take a captured ship into a neutral port without internment only in case of
stress of weather, want of fuel and provisions, or necessity of repairs. In all other cases, the neutral is obligated to
intern the prize crew and restore the vessel to her former crew.”).
198 HAGUE XIII art. 23 (“A neutral Power may allow prizes to enter its ports and roadsteads, whether under convoy
or not, when they are brought there to be sequestrated pending the decision of a Prize Court. It may have the prize
taken to another of its ports. If the prize is convoyed by a war-ship, the prize crew may go on board the convoying
ship. If the prize is not under convoy, the prize crew are left at liberty.”).
199 William H. Taft, Proclamation Regarding the Hague XIII, Feb. 28, 1910, 36 STAT. 2415, 2438 (“And whereas
the Senate of the United States of America by its resolution of April 17, 1908, (two-thirds of the Senators present
concurring therein) did advise and consent to the adherence by the United States to the said Convention with the
reservation and exclusion of its Article 23 and with the understanding that the last clause of Article 3 of the said
Convention implies the duty of a neutral power to make the demand therein mentioned for the return of a ship
captured within the neutral jurisdiction and no longer within that jurisdiction; And whereas the President of the
United States of America, in pursuance of and in conformity with the aforesaid advice and consent of the Senate,
did, on the 23rd day of February, 1909, declare the adherence of the United States to the said Convention;”).
963
15.10 NEUTRAL AIRSPACE
In general, belligerent military aircraft may not enter neutral airspace except to address
violations of neutrality by enemy forces when the neutral State is unwilling or unable to address
such violations.
15.10.1 Airspace That Is Considered Neutral. The airspace over a neutral State’s land
territory and the neutral State’s territorial and archipelagic waters is subject to the sovereignty of
the neutral State and, thus, is considered neutral.200
The airspace over international waters, including the airspace over a neutral State’s
contiguous zone and exclusive economic zone, is not considered neutral airspace.201
15.10.2 Prohibition on Entry by Belligerent Military Aircraft Into Neutral Airspace.
Belligerent military aircraft are forbidden to enter neutral airspace, subject to certain
exceptions.202
Belligerent military aircraft have the right to pass through international straits overlapped
by neutral waters and archipelagic sea lanes of a neutral State.203
Belligerent States’ medical aircraft may enter neutral airspace subject to certain
conditions.204
Belligerent aircraft in evident distress may be permitted to enter neutral airspace and to
land in neutral territory under such safeguards as the neutral State may wish to impose. The
neutral State must require such aircraft to land and must intern both aircraft and crew.205 This
200 Refer to § 14.2.1.1 (National Airspace).
201 Refer to § 14.2.1.2 (International Airspace).
202 Consultative Meeting of Foreign Ministers of the American Republics, Final Act of the Meeting: V General
Declaration of Neutrality of the American Republics, ¶3, Oct. 3, 1939, 1 DEPARTMENT OF STATE BULLETIN 326, 327
(Oct. 7, 1939) (The American Republics resolve “[t]o declare that with regard to their status as neutrals, there exist
certain standards recognized by the American Republics applicable in these circumstances and that in accordance
with them they: ... (f) Shall regard as a contravention of their neutrality any flight by the military aircraft of a
belligerent state over their own territory.”).
203 Refer to § 15.8 (Passage of Belligerent Vessels and Aircraft Through International Straits and Archipelagic Sea
Lanes).
204 Refer to § 15.18.2 (Medical Aircraft and Neutral Territory).
205 2007 NWP 1-14M ¶7.3.9 (“Belligerent aircraft in evident distress may be permitted to enter neutral airspace and
to land in neutral territory under such safeguards as the neutral nation may wish to impose. The neutral nation must
require such aircraft to land and must intern both aircraft and crew.”). See also SPAIGHT, AIR POWER AND WAR
RIGHTS 436 (“The case of distress.—It was agreed by the Commission of Jurists of 1922-23 that the obligation to
prevent the entry of belligerent military aircraft was to be regarded as being subject to the neutral State’s moral duty
to grant succor to airmen in distress. As already explained, there is, in practice, some difficulty in differentiating
between cases in which the reason for entry is genuine distress, or some similar cause such as engine failure or
exhaustion of fuel which might lead to disaster, and those in which there is a deliberate attempt to penetrate in order
to secure some military advantage or to escape from superior forces. The highest that one can put the neutral
obligation is that asylum should be granted in all cases of evident distress, so far as the circumstances allow this
obvious concession to humanitarian claims to be made.”).
964
situation would fall under the general duty of a neutral State with respect to the treatment of
belligerent State forces that enter, or seek to enter, its territory.206
15.10.3 Duties of Neutral States With Respect to Their Airspace. As with other neutral
territory, neutral States have an affirmative duty to prevent the violation of their airspace by
belligerent military aircraft.207 For example, if a belligerent military aircraft enters neutral
airspace, the neutral State is obliged to use the means at its disposal to require the belligerent
military aircraft to land within its territory.208 After the aircraft lands, the neutral State must
intern the aircraft and its crew for the duration of the armed conflict.
If a neutral State is unable or unwilling to prevent the unlawful entry or use of its airspace
by a belligerent State, the opposing belligerent State’s forces may undertake such self-help
enforcement measures as the circumstances may require.209 For example, belligerents with
missile defense capabilities may be justified in intercepting enemy missiles transiting neutral
airspace if the neutral state cannot, or will not, prevent such airspace incursions.
15.11 BELLIGERENT RIGHT OF ANGARY
The right of angary recognizes the right of belligerents to requisition (upon payment of
just compensation) neutral property transiently within their territory, or in territory that they have
occupied, where the property is urgently required for the conduct of the war.210
15.11.1 Neutral Property Transiently Within Belligerent Jurisdiction. The belligerent
right of angary applies to property that is transiently within belligerent jurisdiction. For example,
neutral ships have been subject of the exercise of the right of angary.211
206 Refer to § 15.16 (Belligerent Forces Taking Refuge in Neutral Territory).
207 See, e.g., TUCKER, THE LAW OF WAR AND NEUTRALITY AT SEA 251 (“The practices of states during World Wars
I and II may be regarded as having firmly established both the right as well as the duty of the neutral state to forbid
the entrance of belligerent military aircraft into its air space.”); SPAIGHT, AIR POWER AND WAR RIGHTS 420 (“The
important question whether the laws of neutrality allow belligerent military aircraft to come and go in neutral
jurisdiction was answered by the practice of 1914-18 with a firm and unmistakable negative. The unanimity of the
answer was remarkable. All the neutral States who had occasion to decide the question decided it in the same
general way, and their decision gave rise to no protest on the part of the belligerents concerned, with one single
exception, which the subsequent action and compliance of the State making it deprived of all its force.”).
208 Consider Commission of Jurists to Consider and Report Upon the Revision of the Rules of Warfare, General
Report, Part II: Rules of Aërial Warfare, art. 42, Feb. 19, 1923, reprinted in 32 AJIL SUPPLEMENT: OFFICIAL
DOCUMENTS 12, 36 (1938) (“A neutral government must use the means at its disposal to prevent the entry within its
jurisdiction of belligerent military aircraft and to compel them to alight if they have entered such jurisdiction. A
neutral government shall use the means at its disposal to intern any belligerent military aircraft which is within its
jurisdiction after having alighted for any reason whatsoever, together with its crew and the passengers, if any.”).
209 Refer to § 15.4.2 (Belligerent Use of Self-Help When Neutral States Are Unable or Unwilling to Prevent
Violations of Neutrality).
210 GREENSPAN, MODERN LAW OF LAND WARFARE 581 (“The right of angary, an ancient rule of international law, in
its modern application recognizes the right of belligerents to requisition (upon payment of just compensation)
neutral ships and other neutral property transiently within their territory, or in territory which they have occupied,
where the property is urgently required for the conduct of the war.”).
965
The right of angary does not apply to property of neutral ownership that has acquired
enemy character.212
15.11.2 Railway Material Coming From the Territory of a Neutral State. Railway
material coming from the territory of a neutral State, whether it be the property of that State or of
companies or private persons, and recognizable as such, shall not be requisitioned or utilized by
a belligerent State except where and to the extent that it is absolutely necessary.213 It shall be
sent back as soon as possible to the country of origin.214 A neutral State may likewise, in case of
necessity, retain and utilize to an equal extent railway material coming from the territory of a
belligerent State.215 Compensation shall be paid by one party or the other in proportion to the
railway material used, and to the period of usage.216
Railway materials would include, for example, railroad cars and locomotives.
211 For example, Press Release: Swedish Motorship “Kungsholm,” 5 DEPARTMENT OF STATE BULLETIN 519 (Dec.
13, 1941) (“The United States Government has exercised its right of angary to take over the Swedish motorship
Kungsholm.”); Woodrow Wilson, Proclamation Concerning the Possession and Utilization of Netherlands Vessels,
Mar. 20, 1918, reprinted in 12 AJIL SUPPLEMENT: OFFICIAL DOCUMENTS 259-60 (1918) (“Whereas the law and
practice of nations accords to a belligerent Power the right in time of military exigency and for purposes essential to
the prosecution of the war, to take over and utilize neutral vessels lying within its jurisdiction: … Now therefore I,
Woodrow Wilson, President of the United States of America, in accordance with international law and practice, and
by virtue of the Act of Congress aforesaid, and as Commander-in-Chief of the Army and Navy of the United States,
do hereby find and proclaim that the imperative military needs of the United States require the immediate utilization
of vessels of Netherlands registry, now lying within the territorial waters of the United States; and I do therefore
authorize and empower the Secretary of the Navy to take over on behalf of the United States the possession of and to
employ all such vessels of Netherlands registry as may be necessary for essential purposes connected with the
prosecution of the war against the Imperial German Government. The vessels shall be manned, equipped, and
operated by the Navy Department and the United States Shipping Board, as may be deemed expedient; and the
United States Shipping Board shall make to the owners thereof full compensation, in accordance with the principles
of international law.”).
212 LAUTERPACHT, II OPPENHEIM’S INTERNATIONAL LAW 761-62 (§365) (“In case property of subjects of neutral
States is vested with enemy character, it is not neutral property in the strict sense of the term ‘neutral,’ and all rules
respecting appropriation, utilization, and destruction of enemy property obviously apply to it. The object of the right
of angary is, therefore, either such property of subjects of neutral States as retains its neutral character from its
temporary position on belligerent territory, and which therefore is not vested with enemy character, or such neutral
property on the open sea as has not acquired enemy character.”).
213 HAGUE V art. 19 (“Railway material coming from the territory of neutral Powers, whether it be the property of
the said Powers or of Companies or private persons, and recognizable as such, shall not be requisitioned or utilized
by a belligerent except where and to the extent that it is absolutely necessary.”).
214 HAGUE V art. 19 (“It shall be sent back as soon as possible to the country of origin.”).
215 HAGUE V art. 19 (“A neutral Power may likewise, in case of necessity, retain and utilize to an equal extent
material coming from the territory of the belligerent Power.”).
216 HAGUE V art. 19 (“Compensation shall be paid by one party or the other in proportion to the material used, and to
the period of usage.”).
966
This rule on railway material has sought to balance between the necessities of war (i.e.,
that such material might be of great military utility) and the interests and rights of neutrals.217
This rule also reflects a compromise between the different views of States.218
15.12 NEUTRAL COMMERCE AND CARRIAGE OF CONTRABAND
Although neutral States must not provide war-related goods and services to belligerents,
neutral persons are not prohibited from such activity by the law of neutrality.219 The law of
neutrality’s rules on neutral commerce and the carriage of contraband have sought to balance the
right of neutral persons to conduct commerce free from unreasonable interference against the
right of belligerent States to interdict the passage of war materials to the enemy.220
Neutral merchant vessels and civil aircraft engaged in legitimate neutral commerce are
subject to visit and search, but generally may not be captured or destroyed by belligerent
forces.221 On the other hand, neutral merchant vessels and civil aircraft are subject to capture
and other penalties if they engage in certain conduct.222
217 Antonio S. de Bustamante, The Hague Convention Concerning the Rights and Duties of Neutral Powers and
Persons in Land Warfare, 2 AJIL, 95, 119 (1908) (“The article in regard to railways - the only article saved in the
chapter relating to foreign property - is useful to nations with land boundaries and is based on just terms, making the
best equivalent for the necessities of war and in the interest and right of neutrals. Therefore, its acceptance brings
great credit upon the delegation of Luxemburg. It is to be observed that the final redaction only relates to railway
material coming from neutral states, belonging to the said states or to companies or private persons. It has no other
purpose than to facilitate the return of the compensation or the payment for the use of the cars and locomotives of a
country which may accidentally enter the other state through the occasions of ordinary traffic.”).
218 See A. PEARCE HIGGINS, THE HAGUE PEACE CONFERENCES AND OTHER INTERNATIONAL CONFERENCES
CONCERNING THE LAWS AND USAGES OF WAR: TEXTS OF CONVENTIONS WITH COMMENTARIES 294 (1909) (“Article
19 replaces Article 54 of the Regulations of 1899 and is a compromise between contradictory views. Luxemburg
and Belgium denied the right of belligerents to requisition and make use of neutral railway materials within their
territory. Germany and Austria desired to have the right to use it admitted, on the understanding that an indemnity
was paid for its use after the close of the war. France and Luxemburg as an alternative claimed both an indemnity
and the right, in case of need, to retain and make use of a corresponding quantity of railway material coming from
the territory of a belligerent state. The Conference took the middle course, allowing belligerents to requisition and
use neutral railway material only when absolutely necessary, on condition that it be returned as soon as possible, the
neutral being given the corresponding right over belligerent material within its territory, compensation to be paid by
one party to the other in proportion to the material used and the period of use.”).
219 Refer to § 15.3.2.1 (Duty to Refrain From Providing War-Related Goods and Services to Belligerents).
220 TUCKER, THE LAW OF WAR AND NEUTRALITY AT SEA 182 (“It has long been customary to characterize the
problems arising with respect to neutral commerce in terms of two conflicting rights: the right of the neutral state to
insist upon continued freedom of commerce for its subjects despite the existence of war and the right of the
belligerent to prevent neutral subjects from affording assistance to the military effort of an enemy. More accurate,
perhaps, is the characterization of these problems in terms of conflicting interests rather than in terms of conflicting
rights. Whereas the neutral’s interest has been to suffer the least amount of belligerent interference in the trading
activities of its subjects, the belligerent’s interest has been to prevent neutrals from compensating for an enemy's
weakness at sea.”).
221 Refer to § 15.13 (Belligerent Right of Visit and Search of Merchant Vessels and Civil Aircraft).
222 Refer to § 15.15.1 (Grounds for the Capture of Neutral Vessels and Aircraft).
967
Contraband goods are liable to capture at any place beyond neutral territory, if their
destination is the territory belonging to, or occupied by, an opposing belligerent State.223
15.12.1 Classes of Goods That May Be Considered Contraband. Contraband consists of
goods that are destined for an enemy of a belligerent and that may be susceptible to use in armed
conflict.224 Items susceptible to use in armed conflict may be understood to include war-
sustaining commerce, i.e., commerce that indirectly but effectively supports and sustains the
belligerent State’s war fighting capability (e.g., imports of raw materials used for the production
of armaments and exports of products whose proceeds are used by the belligerent State to
purchase arms and armaments).225
15.12.1.1 Distinction Between Absolute and Conditional Contraband. Whether
an item is susceptible to use in armed conflict may depend on the character of the item.
Traditionally, contraband has been divided into two categories, absolute and conditional.
Absolute contraband consisted of goods whose character is such that they are obviously destined
for use in armed conflict, such as munitions, weapons, uniforms, and the like. Conditional
contraband consisted of goods equally susceptible to either peaceful or warlike purposes, such as
foodstuffs, construction materials, and fuel.226
223 2007 NWP 1-14M ¶7.4.1.2 (“Contraband goods are liable to capture at any place beyond neutral territory, if their
destination is the territory belonging to or occupied by the enemy.”); 1998 NWP 9 ¶7.4.1.1 (same).
224 2007 NWP 1-14M ¶7.4.1 (“Contraband consists of goods destined for the enemy of a belligerent and that may be
susceptible to use in armed conflict.”); 1955 NWIP 10-2 ¶631a (“Contraband consists of all goods which are
destined for an enemy and which may be susceptible of use in war.”).
225 See 2007 NWP 1-14M ¶7.4 (“For purposes of this publication, neutral commerce comprises all commerce
between one neutral nation and another not involving materials of war or armaments ultimately destined for a
belligerent nation, and all commerce between a neutral nation and a belligerent that does not involve the carriage of
contraband or otherwise contribute to the belligerent’s war-fighting/war-sustaining capability.”); 1998 NWP 9 ¶7.4
footnote 88 (“Although war-sustaining commerce is not subject to precise definition, commerce that indirectly but
effectively supports and sustains the belligerent's war-fighting capability properly falls within the scope of the term.
Examples of war-sustaining commerce include imports of raw materials used for the production of armaments and
exports of products the proceeds of which are used by the belligerent to purchase arms and armaments.”) (internal
citations omitted).
226 2007 NWP 1-14M ¶7.4.1 (“Contraband consists of goods destined for the enemy of a belligerent and that may be
susceptible to use in armed conflict. Traditionally, contraband has been divided into two categories: absolute and
conditional. Absolute contraband consisted of goods the character of which made it obvious that they were destined
for use in armed conflict, such as munitions, weapons, uniforms, and the like. Conditional contraband consisted of
goods equally susceptible to either peaceful or warlike purposes, such as foodstuffs, construction materials, and
fuel.”). See also The Peterhoff, 72 U.S. 28, 52-53 (1867) (“The classification of goods as contraband or not
contraband has much perplexed text writers and jurists. A strictly accurate and satisfactory classification is perhaps
impracticable; but that which is best supported by American and English decisions may be said to divide all
merchandise into three classes. Of these classes, the first consists of articles manufactured and primarily and
ordinarily used for military purposes in time of war; the second, of articles which may be and are used for purposes
of war or peace, according to circumstances; and the third, of articles exclusively used for peaceful purposes.
Merchandise of the first class, destined to a belligerent country or places occupied by the army or navy of a
belligerent, is always contraband; merchandise of the second class is contraband only when actually destined to the
military or naval use of a belligerent; while merchandise of the third class is not contraband at all, though liable to
seizure and condemnation for violation of blockade or siege.”).
968
Whether it is possible to distinguish between absolute contraband and conditional
contraband may depend on the extent to which the enemy government controls imports and the
scale of the conflict. For example, during World War II, belligerent States largely did not
distinguish between absolute and conditional contraband because of the involvement of virtually
the entire population in support of the war effort and because the belligerent States exercised
governmental control over all imports.227
15.12.1.2 Free Goods That Are Exempt From Capture as Contraband. Certain
goods qualify as “free goods,” meaning that they are exempt from capture by belligerent States
as contraband even though they are destined for enemy territory. Free goods include the
following:
• equipment exclusively intended for the treatment of wounded and sick members of armed
forces or for the prevention of disease, provided that the particulars regarding the voyage
of such equipment have been notified to and approved by the opposing belligerent
State;228
• consignments of certain types of relief goods (e.g., medical supplies and religious
materials for civilians; clothing and medicine for children under fifteen, expectant
mothers, and maternity cases), under certain conditions;229
• certain types of relief consignments intended for the benefit of the population of occupied
territory;230
• items destined for POWs, including individual parcels and collective relief shipments
containing food, clothing, medical supplies, religious objects, and educational, cultural,
and athletic articles;231 and
• other goods that are specifically exempted from capture by an applicable treaty or by a
special arrangement between belligerent States.232
227 2007 NWP 1-14M ¶7.4.1 (“The practice of belligerents during the Second World War collapsed the traditional
distinction between absolute and conditional contraband. Because of the involvement of virtually the entire
population in support of the war effort, the belligerents of both sides tended to exercise governmental control over
all imports. Consequently, it became increasingly difficult to draw a meaningful distinction between goods destined
for an enemy government and its armed forces and goods destined for consumption by the civilian populace. As a
result, belligerents treated all imports directly or indirectly sustaining the war effort as contraband without making a
distinction between absolute and conditional contraband.”).
228 Refer to § 7.13 (Chartered Medical Transport Ships).
229 Refer to § 5.19.3 (Passage of Relief Consignments).
230 Refer to § 11.17 (Relief).
231 Refer to § 9.20.3 (Receipt of Individual and Collective Relief Shipments for POWs).
232 For example, HAGUE XI art. 1 (“The postal correspondence of neutrals or belligerents, whatever its official or
private character may be, found on the high seas on board a neutral or enemy ship, is inviolable. If the ship is
detained, the correspondence is forwarded by the captor with the least possible delay.”). See also TUCKER, THE
LAW OF WAR AND NEUTRALITY AT SEA 91 (“From a formal point of view it must probably be concluded that these
provisions remain binding today upon the parties to Hague Convention XI. On the other hand, it is difficult to avoid
969
In practice, neutral States have provided belligerent States of both sides with information
regarding the nature, timing, and route of shipments of goods constituting exceptions to
contraband, and obtained approval for their safe conduct and entry into belligerent owned or
occupied territory.233
15.12.1.3 Contraband Lists. Belligerent States may declare contraband lists at the
initiation of hostilities to notify neutral States of the type of goods considered to be absolute or
conditional contraband, as well as those not considered to be contraband at all (i.e., exempt or
“free goods”). The precise nature of a belligerent State’s contraband list may vary according to
the circumstances of the conflict.234
Although there has been no conflict of a similar scale and magnitude to World War II, in
the years following the conclusion of that conflict State practice indicates that, to the extent
international law may continue to require publication of contraband lists, the requirement may be
satisfied by a listing of exempt goods.235
15.12.2 Requirement of Enemy Destination. Contraband goods are liable to capture at
any place beyond neutral territory if their destination is the territory belonging to, or occupied
by, the enemy.
15.12.2.1 Ultimate Destination - Doctrine of Continuous Voyage. It is immaterial
whether the carriage of contraband is direct, involves transshipment, or requires overland
transport.236 Under the doctrine of continuous voyage, the ultimate destination is determinative,
the conclusion that the events of the two World Wars have reduced the significance of these provisions almost to a
vanishing point.”).
233 1989 NWP 9 ¶7.4.1.2 (“It is customary for neutral nations to provide belligerents of both sides with information
regarding the nature, timing, and route of shipments of goods constituting exceptions to contraband and to obtain
approval for their safe conduct and entry into belligerent owned or occupied territory.”). Compare § 5.19.3.1
(Technical Arrangements for the Passage and Distribution of Relief Consignments).
234 2007 NWP 1-14M ¶7.4.1 (“Belligerents may declare contraband lists at the initiation of hostilities to notify
neutral nations of the type of goods considered to be absolute or conditional contraband, as well as those not
considered to be contraband at all (i.e., exempt or “free goods”). The precise nature of a belligerent’s contraband list
may vary according to the circumstances of the conflict.”); 1955 NWIP 10-2 ¶631b (“BELLIGERENT
CONTRABAND DECLARATIONS. Upon the initiation of armed conflict, belligerents may declare contraband
lists, setting forth therein the classification of articles to be regarded as contraband, as well as the distinction to be
made between goods considered as absolute contraband and goods considered as conditional contraband. The
precise nature of a belligerent’s contraband list may vary according to the particular circumstances of the armed
conflict.”).
235 2007 NWP 1-14M ¶7.4.1 (“Though there has been no conflict of similar scale and magnitude since the Second
World War, post-World War II-practice indicates that, to the extent international law may continue to require
publication of contraband lists, the requirement may be satisfied by a listing of exempt goods.”).
236 2007 NWP 1-14M ¶7.4.1.2 (“It is immaterial whether the carriage of contraband is direct, involves
transshipment, or requires overland transport.”); 1998 NWP 9 ¶7.4.1.1 (same). Consider 1909 DECLARATION OF
LONDON art. 30 (“Absolute contraband is liable to capture if it is shown to be destined to territory belonging to or
occupied by the enemy, or to the armed forces of the enemy. It is immaterial whether the carriage of the goods is
direct or entails transhipment or a subsequent transport by land.”).
970
and contraband goods may be captured, even if there are neutral ports that are intended to be
visited between the point of capture and the ultimate destination.237
15.12.2.2 Presumption of Destination of Enemy Territory in Certain Cases.
When contraband is involved, a destination of enemy-owned or enemy-occupied territory may be
presumed when:
• the neutral vessel is to call at an enemy port before arriving at a neutral port for which the
goods are documented;
• the goods are documented to a neutral port serving as a port of transit to an enemy, even
though they are consigned to a neutral; or
• the goods are consigned “to order” or to an unnamed consignee, but are destined for a
neutral State in the vicinity of enemy territory.238
These presumptions of enemy destination constitute sufficient cause for naval
commanders to order a capture.239 However, these presumptions may be rebuttable during
subsequent prize court proceedings by an affirmative showing of innocent destination.240
237 The Pedro, 175 U.S. 354, 365-66 (1899) (“In The Circassian, it was ruled that the intent to violate a blockade,
found as a fact, was not disproved by evidence of a purpose to call at a neutral port, not reached at time of capture,
with ulterior destination to the blockaded port. In The Bermuda, the actual destination to a belligerent port, whether
ulterior or direct, was held to determine, the character of the transaction as a whole; that transhipment could not
change the effect of the pursuit of a common object by a common plan; and that if the cargo was contraband its
condemnation was justified, whether the voyage was to ports blockaded or to ports not blockaded; and so as to the
vessel in the former case. And in The Springbok, it was held that an intention to tranship cargo at a neutral port did
not save it when destined for a blockaded port; that as to cargo, both in law and intent, the voyage from London to
the blockaded port was one voyage, and that the liability attached from the time of sailing if captured during any part
of that voyage.”).
238 2007 NWP 1-14M ¶7.4.1.2 (“When contraband is involved, a destination of enemy owned or occupied territory
may be presumed when: 1. The neutral vessel is to call at an enemy port before arriving at a neutral port for which
the goods are documented; 2. The goods are documented to a neutral port serving as a port of transit to an enemy,
even though they are consigned to a neutral; or 3. The goods are consigned ‘to order’ or to an unnamed consignee,
but are destined for a neutral nation in the vicinity of enemy territory.”); 1998 NWP 9 ¶7.4.1.1 (substantially the
same).
239 1955 NWIP 10-2 ¶631c(1) note 21 (“The circumstances creating a presumption of ultimate enemy destination
enumerated in subparagraphs 631c 1 and 2 are of concern to operating naval commanders for the reason that
circumstances held to create a presumption of enemy destination constitute sufficient cause for capture. Before a
prize court each of these presumptions is rebuttable and whether or not a prize court will, in fact, condemn the
captured cargo, and vessel (or aircraft), will depend upon a number of complex considerations with which an
operating naval commander need not be concerned.”).
240 See TUCKER, THE LAW OF WAR AND NEUTRALITY AT SEA 272-73 (“In this connection the belligerent’s task has
been facilitated still further by the creation of a detailed set of presumptions governing hostile destination. Thus a
presumption of enemy destination has been held to arise where goods are consigned ‘to order,’ or if the ships papers
do not indicate the real consignee of the goods, or if goods are merely consigned to a dealer or agent and the
ultimate buyer is unknown, or if the parties engaged in the transaction—though known—have or are suspected of
having enemy connections. In any of the foregoing circumstances the inference of an ultimate enemy destination
has been strong and could be displaced only by a positive showing that the goods in question had an innocent
destination.”).
971
These presumptions of the destination of enemy territory are not sufficient to establish
that the property is destined for use by an enemy government or its armed forces, which would
be necessary to establish a basis for the forfeiture of the property if the property is classified as
conditional contraband.241
15.12.3 Certificate of Noncontraband Carriage. A certificate of noncontraband carriage
is a document issued by a belligerent consular or other designated official to a neutral vessel
(navicert) or neutral aircraft (aircert) certifying that the cargo being carried has been examined,
usually at the initial place of departure, and has been found to be free of contraband. The
purpose of such a navicert or aircert is to facilitate belligerent control of contraband goods with
minimal interference and delay of neutral commerce.242 The navicert or aircert may be viewed
as a type of commercial passport.243
The certificate is not a guarantee that the vessel or aircraft will not be subject to visit and
search or that cargo will not be seized. (Changed circumstances, such as a change in status of the
neutral vessel, between the time of issuance of the certificate and the time of interception at sea
may cause it to be invalidated.) Conversely, the absence of a navicert or aircert is not, in itself, a
valid ground for seizure of cargo.244
Navicerts and aircerts issued by one belligerent State do not limit the visit and search
rights of an opposing belligerent State. When a neutral ship or aircraft accepts a navicert or
aircert from one belligerent State, this may affect how the other belligerent State views the
neutrality of that aircraft or vessel.245
241 Refer to § 15.12.1.1 (Distinction Between Absolute and Conditional Contraband).
242 2007 NWP 1-14M ¶7.4.2 (“A certificate of noncontraband carriage is a document issued by a belligerent consular
or other designated official to a neutral vessel (navicert) or neutral aircraft (aircert) certifying that the cargo being
carried has been examined, usually at the initial place of departure, and has been found to be free of contraband.
The purpose of such a navicert or aircert is to facilitate belligerent control of contraband goods with minimal
interference and delay of neutral commerce.”); 1998 NWP 9 ¶7.4.2 (same).
243 See Malcolm Moos, The Navicert in World War II, 38 AJIL 115 (1944) (“In view of their favorable experience
with the ‘navicert’ during World War I, its revival by the British in December 1939, occasioned no surprise. The
term navicert is derived from the code word ‘navicert,’ and in essence is a commercial passport designed to
facilitated the passage of consignments through the British blockade.”). Refer to § 12.6 (Military Passports, Safe-
Conducts, and Safeguards).
244 2007 NWP 1-14M ¶7.4.2 (“The certificate is not a guarantee that the vessel or aircraft will not be subject to visit
and search or that cargo will not be seized. (Changed circumstances, such as a change in status of the neutral vessel,
between the time of issuance of the certificate and the time of interception at sea may cause it to be invalidated.)
Conversely, absence of a navicert or aircert is not, in itself, a valid ground for seizure of cargo.”); 1998 NWP ¶7.4.2
(same).
245 See TUCKER, THE LAW OF WAR AND NEUTRALITY AT SEA 322-23 (“In this connection a problem of considerable
importance arises as a result of the attempt by belligerents to institute a system of passes for neutral shipping. In
principle, it is clear that such devices as the navicert and ships warrant are intended to establish an effective control
over the activities of neutral merchant vessels. Neutral merchant vessels by submitting to such a system thereby
ease the belligerent's task of patrolling the high seas in search either of contraband carriers or of blockade runners.
It seems reasonably well-established that a neutral merchant vessel in accepting a safe-conduct pass from a
belligerent subjects itself to the control of the latter and performs an act of unneutral service. The same conclusion
972
A similar procedure was used during the Cuban Missile Crisis, when the United States
issued clearance certificates (clearcerts).246
15.13 BELLIGERENT RIGHT OF VISIT AND SEARCH OF MERCHANT VESSELS AND CIVIL AIRCRAFT
Belligerent warships and military aircraft have a right of visit and search of merchant
vessels and civil aircraft outside of neutral territory.
15.13.1 Purposes of Visit and Search. The belligerent right of visit and search may be
viewed as a necessary part of the belligerent’s right to capture enemy merchant vessels and civil
aircraft, and to capture neutral merchant vessels and civil aircraft that have engaged in violations
of neutrality.247 Thus, for example, visit and search has been conducted with the object of:248
• ascertaining the character of the vessel or aircraft and nationality (including assessing
whether a vessel or aircraft that is flagged to a neutral State has acquired enemy character
by engaging in service to the enemy);249
• verifying whether it conveys contraband cargo;250
• verifying whether it has committed a breach of blockade;251 or
• verifying whether the vessel or aircraft has committed another violation of neutrality
making it liable to capture.252
would appear warranted in the case of a neutral vessel that cooperates with a belligerent by voluntarily applying for,
and accepting, a navicert or ship’s warrant.”).
246 Press Release: U.S. Acts To Avoid Delays for Ships Transiting Waters in Vicinity of Cuba, Oct. 27, 1962, 47
DEPARTMENT OF STATE BULLETIN 747 (Nov. 12, 1962) (“The Department of State announced on October 27 the
institution of a system of clearances to assist vessels which transit waters in the vicinity of Cuba and vessels destined
for Cuban ports with cargoes containing no offensive weapons or associated materiel. The system, developed by the
State, Defense, and Treasury Departments, is designed to avoid unnecessary delays and other difficulties arising out
of the stoppage, inspection, or possible diversion of ships. The system is for the convenience of shipping, and
clearances are obtainable upon application by ships’ owners, agents, or officers. A vessel departing a United States
port may obtain a special clearance from customs authorities at the port of departure. A vessel departing a foreign
port may obtain the clearance from an American consulate.”).
247 See, e.g., The Nereide, 13 U.S. 388, 427-28 (1815) (“Belligerents have a full and perfect right to capture enemy
goods and articles going to their enemy which are contraband of war. To the exercise of that right the right of search
is essential. It is a mean justified by the end. It has been truely denominated a right growing out of, and ancillary to
the greater right of capture. Where this greater right may be legally exercised without search, the right of search can
never arise or come into question.”).
248 1928 PAN AMERICAN MARITIME NEUTRALITY CONVENTION art. 1(1) (“Warships of the belligerents have the right
to stop and visit on the high seas and in territorial waters that are not neutral any merchant ship with the object of
ascertaining its character and nationality and of verifying whether it conveys cargo prohibited by international law
or has committed any violation of blockade.”).
249 Refer to § 15.14 (Acquisition of Enemy Character by Neutral-Flagged Merchant Vessels and Neutral-Marked
Civil Aircraft).
250 Refer to § 15.12 (Neutral Commerce and Carriage of Contraband).
251 Refer to § 13.10 (Blockade).
973
15.13.2 Types of Neutral Vessels and Aircraft That Are Exempt From Visit and Search.
Certain neutral vessels and aircraft are exempt from the belligerent right of visit and search: (1)
neutral warships; (2) neutral State aircraft (including military aircraft); (3) ships of neutral States
used only on government non-commercial service; and (4) neutral merchant vessels under
convoy of neutral warships of the same nationality, and neutral aircraft accompanied by neutral
military aircraft of the same nationality.
15.13.2.1 Neutral Warships. Neutral warships may not be subjected to visit and
search because they have complete immunity from the jurisdiction of any State other than the
flag State.253
15.13.2.2 Neutral State Aircraft. Neutral State aircraft (including military
aircraft) are immune from visit and search by foreign States.254
15.13.2.3 Ships of a Neutral State Used Only on Government Non-Commercial
Service. Ships owned or operated by a neutral State and used only on government non-
commercial service may not be subjected to visit and search because they also have complete
immunity from the jurisdiction of any State other than the flag State.255
15.13.2.4 Neutral Merchant Vessels Under Convoy of Neutral Warships of the
Same Nationality and Neutral Aircraft Accompanied by Neutral Military Aircraft of the Same
Nationality. Neutral merchant vessels under convoy of neutral warships of the same nationality
are also exempt from visit and search.256 However, the convoy commander may be required to
provide in writing to the commanding officer of an intercepting belligerent State’s warship
information as to the character of the vessels and their cargoes that would otherwise be obtained
by a visit and search.257 Neutral merchant vessels under convoy of neutral warships of the same
252 Refer to § 15.15.1 (Grounds for the Capture of Neutral Vessels and Aircraft).
253 Consider LOS CONVENTION art. 95 (“Warships on the high seas have complete immunity from the jurisdiction of
any State other than the flag State.”).
254 Refer to § 14.3.1 (State Versus Civil Aircraft); 14.3.3.1 (Military Aircraft - Rights and Liabilities).
255 Consider LOS CONVENTION art. 96 (“Ships owned or operated by a State and used only on government non-
commercial service shall, on the high seas, have complete immunity from the jurisdiction of any State other than the
flag State.”).
256 For example, John H. McNeill, Neutral Rights and Maritime Sanctions: The Effects of Two Gulf Wars, 31
VIRGINIA JOURNAL OF INTERNATIONAL LAW 631, 635 (1991) (“And in July 1987, eleven Kuwaiti-owned tankers
were registered under the U.S. flag and escorted by the U.S. Navy. To many, this reflagging procedure appeared to
be a logical expedient, not for repudiating the rules concerning contraband, but rather for protecting these vessels
against the attack-on-sight of neutral shipping, in addition to whatever U.S. foreign policy objectives the reflagging
served. In effect, the U.S. relied upon the ancient doctrine of ‘right of convoy’ under which belligerents cannot visit
and search convoyed ships and are to be satisfied with the declaration of the commander of the convoy that no cargo
which can be considered contraband is on board the convoyed ships.”).
257 Consider 1909 DECLARATION OF LONDON art. 61 (“Neutral vessels under national convoy are exempt from
search. The commander of a convoy gives, in writing, at the request of the commander of a belligerent warship, all
information as to the character of the vessels and their cargoes, which could be obtained by search.”).
974
nationality are exempt from visit and search because the neutral State has provided an assurance
that the neutral vessel is not engaged in violations of neutrality.258
If a convoy commander determines that a vessel under his or her charge possesses enemy
character or carries contraband cargo, the commander is obliged to withdraw his or her
protection from the offending vessel, making it liable to visit and search, and possible capture, by
opposing belligerent warships.259
Neutral civil aircraft accompanied by neutral military aircraft of the same flag may also
be exempt from visit and search if the following two elements are met:
• the flag State of a neutral military aircraft warrants that the neutral civil aircraft is not
carrying contraband cargo; and
• the commander of the neutral military aircraft provides to the intercepting belligerent
military aircraft upon request all information as to the character and cargo of the neutral
civil aircraft that would otherwise be obtained by a visit and search.260
15.13.3 Where Belligerents May Not Exercise the Right of Visit and Search. As an act of
hostility, the belligerent right of visit and search may not be conducted within neutral territory
(e.g., a neutral State’s territorial seas and neutral airspace).261 This prohibition on the exercise of
the belligerent right of visit and search extends to international straits overlapped by neutral
territorial seas and to archipelagic sea lanes.262
258 See General Report to the Conference, reprinted in JAMES BROWN SCOTT, THE DECLARATION OF LONDON
FEBRUARY 26, 1909 177-78 (1920) (“The principle laid down is simple; a neutral vessel under the convoy of a war-
ship of her own nationality is exempt from search. The reason for this rule is that the belligerent cruiser ought to be
able to find in the assurances of the commander of the convoy as good a guaranty as would be afforded by the
exercise of the right of search itself; in fact, she can not call in question the assurances given by the official
representative of a neutral Government without displaying a lack of international courtesy.”).
259 Consider 1909 DECLARATION OF LONDON art. 62 (“If the commander of the belligerent warship has reason to
suspect that the confidence of the commander of the convoy has been abused, he communicates his suspicions to
him. In such a case it is for the commander of the convoy alone to investigate the matter. He must record the result
of such investigation in a report, of which a copy is handed to the officer of the warship. If, in the opinion of the
commander of the convoy, the facts shown in the report justify the capture of one or more vessels, the protection of
the convoy must be withdrawn from such vessels.”).
260 2007 NWP 1-14M ¶7.6.3 (“Neutral civilian aircraft accompanied by neutral military aircraft of the same flag are
exempt from visit and search if the neutral military aircraft (1) warrants that the neutral civilian aircraft is not
carrying contraband cargo and (2) provides to the intercepting belligerent military aircraft upon request such
information as to the character and cargo of the neutral civilian aircraft as would otherwise be obtained in visit and
search.”).
261 See HAGUE XIII art. 2 (“Any act of hostility, including capture and the exercise of the right of search, committed
by belligerent war-ships in the territorial waters of a neutral Power, constitutes a violation of neutrality and is strictly
forbidden.”); 1928 PAN AMERICAN MARITIME NEUTRALITY CONVENTION art. 1(1) (“Warships of the belligerents
have the right to stop and visit on the high seas and in territorial waters that are not neutral any merchant ship with
the object of ascertaining its character and nationality and of verifying whether it conveys cargo prohibited by
international law or has committed any violation of blockade.”).
262 Refer to § 15.8 (Passage of Belligerent Vessels and Aircraft Through International Straits and Archipelagic Sea
Lanes).
975
15.13.4 Procedure for Visit and Search of Merchant Vessels and Aircraft. Belligerent
States have discretion in formulating their procedures for conducting the visit and search of
neutral merchant vessels and aircraft.263 Generally, the belligerent warship or aircraft visits or
intercepts the vessel or aircraft, shows its true colors, and provides a clear signal to the merchant
vessel or civil aircraft that it is expected to submit to visit and search.264
During armed conflict, specific rules of engagement or other special instructions may be
issued by the operational chain of command to provide guidance on the visit and search
procedure to be carried out by U.S. warships and military aircraft when exercising the belligerent
State’s right of visit and search of merchant vessels and civil aircraft. For example, the issuance
of certificates of non-contraband carriage may be part of such procedures.265 In the absence of
specific guidance from the operational chain of command, Military Department or Service
regulations or guidance may provide the applicable procedures.266
15.13.4.1 Use of Force During Visit and Search. Merchant vessels or civil
aircraft that comply with instructions given to them may not be made the object of attack;
merchant ships or civil aircraft that refuse to comply may be stopped by force.267 Merchant
ships or civil aircraft that resist visit and search assume the risk of resulting damage.268 Such
263 TUCKER, THE LAW OF WAR AND NEUTRALITY AT SEA 336 (“Customary international law does not lay down
detailed rules governing the mode of conducting visit and search and belligerents have always enjoyed a certain
discretion in this regard. In general, however, a substantial measure of uniformity came to characterize the
traditional practices of states, and this uniformity was reflected in the special instructions issued by maritime powers
to their naval forces.”).
264 TUCKER, THE LAW OF WAR AND NEUTRALITY AT SEA 336 (“Before calling upon a neutral merchantman to
submit to visitation a belligerent warship is required to show its true colors. In addition, visitation must be preceded
by a clear signal on the part of the warship that the merchant vessel is expected to stop and bring to. The
notification of intention to visit may be accomplished by any of several means, e. g., by firing a blank charge, by
international flag signal, or even by radio. Nor does international law prescribe the distance a belligerent warship
must keep from the vessel being visited, which may vary according to the conditions of the sea, the size and
character of the visiting warship, and many other factors.”).
265 Refer to § 15.12.3 (Certificate of Noncontraband Carriage).
266 See, e.g., 2007 NWP 1-14M ¶7.6.1 (“In the absence of specific rules of engagement or other special instructions
issued by the operational chain of command during a period of armed conflict, the following procedure should be
carried out by U.S. warships exercising the belligerent right of visit and search of merchant vessels:”).
267 1928 PAN AMERICAN MARITIME NEUTRALITY CONVENTION art. 1(1) (“If the merchant ship does not heed the
signal to stop, it may be pursued by the warship and stopped by force; outside of such a case the ship cannot be
attacked unless, after being hailed, it fails to observe the instructions given it.”).
268 See Eleanor, 15 U.S. 345, 358 (1817) (“To detain for examination is a right which a belligerant may exercise over
every vessel, not a national vessel, that he meets with on the ocean. And whatever may be the injury that casually
results to an individual from the act of another while pursuing the reasonable exercise of an established right, it is his
misfortune. The law pronounces it damnum absque injuria, and the individual from whose act it proceeds is liable
neither at law nor in the forum of conscience. And the principal right necessarily carries with it also all the means
essential to its exercise. Thus, in the present case, a vessel must be pursued in order to be detained for examination.
But if in the pursuit she had been dismasted, and upset or stranded, or run on shore and lost, it would have been an
unfortunate case, but the pursuing vessel would have stood acquitted.”).
976
vessels or aircraft also may be deemed to acquire the character of enemy merchant ships or civil
aircraft.269
15.13.4.2 Visit and Search of Merchant Vessels by Military Aircraft. Belligerent
military aircraft have a right to conduct visit and search of merchant vessels.270
Ordinarily, visit and search of a vessel by a belligerent State’s aircraft is accomplished by
directing and escorting the merchant vessel to the vicinity of a belligerent warship, which would
carry out the visit and search at sea, or to a belligerent port.271
15.13.4.3 Visit and Search of Civil Aircraft by Military Aircraft. Belligerent
military aircraft have a right to conduct visit and search of civil aircraft.272 Such visit and search
is conducted through interception and, if necessary, diversion.273
15.14 ACQUISITION OF ENEMY CHARACTER BY NEUTRAL-FLAGGED MERCHANT VESSELS AND
NEUTRAL-MARKED CIVIL AIRCRAFT
All vessels operating under an enemy flag, and all aircraft bearing enemy markings,
possess enemy character. However, the fact that a ship flies a neutral flag, or that an aircraft
bears neutral markings, does not necessarily establish the neutral character of the vessel or
aircraft. Vessels or aircraft may acquire enemy character from (1) the ownership or control of
the vessel or aircraft, or (2) their conduct.
15.14.1 Acquisition of Enemy Character by Vessels or Aircraft Through Belligerent
Ownership or Control. Any merchant vessel or civil aircraft that is owned or controlled by an
enemy State or person has enemy character, regardless of whether it is operating under a neutral
flag or bears neutral markings.274 A neutral flag or neutral markings cannot serve as a device to
protect vessels or aircraft from seizure whose actual status indicates either continued ownership
or control by individuals who themselves possess enemy character.275 Such vessels may be
269 Refer to § 15.14.2.2 (Acquiring the Character of an Enemy Merchant Vessel or Civil Aircraft).
270 2007 NWP 1-14M ¶7.6.2 (“Although there is a right of visit and search by military aircraft, there is no
established international practice as to how that right is to be exercised.”).
271 2007 NWP 1-14M ¶7.6.2 (“Ordinarily, visit and search of a vessel by an aircraft is accomplished by directing and
escorting the vessel to the vicinity of a belligerent warship, which will carry out the visit and search, or to a
belligerent port.”).
272 2007 NWP 1-14M ¶7.6.3 (“The right of a belligerent military aircraft to conduct visit and search of a civilian
aircraft to ascertain its true identity (enemy or neutral), the nature of its cargo (contraband or ‘free goods’), and the
manner of its employment (innocent or hostile) is now well established in the law of armed conflict.”).
273 Refer to § 14.5.1 (Interception); § 14.5.2 (Diversion of Aircraft).
274 See 1955 NWIP 10-2 ¶501 (“Any merchant vessel or aircraft owned or controlled by or for an enemy State,
enemy persons, or any enemy corporation possesses enemy character, regardless of whether or not such a vessel or
aircraft operates under a neutral flag or bears neutral markings.”).
275 See TUCKER, THE LAW OF WAR AND NEUTRALITY AT SEA 75 (“For the practice of states is clear that even though
entitled to fly a neutral flag—and thus possessing a neutral nationality—a vessel may nevertheless be considered as
impressed with an enemy character. The neutral flag cannot serve as a device to protect vessels from seizure whose
actual status indicates either continued ownership or control by individuals who themselves possess enemy
character.”).
977
subject to treatment as enemy merchant vessels or civil aircraft, including being subject to
capture. 276
15.14.2 Acquisition of Enemy Character by Vessels or Aircraft Through Conduct.
Certain conduct by vessels or aircraft may lead them to acquire enemy character and make them
liable to treatment as either (1) enemy warships or military aircraft, or (2) enemy merchant ships
or civil aircraft.
Humanitarian assistance given to the wounded, sick, or shipwrecked of belligerent forces
by neutral vessels does not lead to such vessels acquiring enemy character if such assistance is
provided in accordance with the GWS-Sea.277
15.14.2.1 Acquiring the Character of an Enemy Warship or Military Aircraft.
Neutral merchant vessels and civil aircraft acquire enemy character, and may be treated by a
belligerent as enemy warships and military aircraft, when engaged in either of the following
acts:278
• taking a direct part in the hostilities on the side of the enemy; or
• acting in any capacity as a naval or military auxiliary to the enemy’s armed forces.279
For example, such vessels and aircraft may be made the object of attack outside of neutral
territory.280
15.14.2.2 Acquiring the Character of an Enemy Merchant Vessel or Civil
Aircraft. Neutral merchant vessels and civil aircraft acquire enemy character and may be treated
276 Refer to § 13.5 (Enemy Merchant Vessels).
277 Refer to § 7.4.6 (Collection and Care of the Wounded, Sick, and Shipwrecked by Neutral Vessels); § 7.12.1.3
(Authorized Neutral Civilian Hospital Ships).
278 See, e.g., 2007 NWP 1-14M ¶7.5.1 (“Neutral merchant vessels and civil aircraft acquire enemy character and
may be treated by a belligerent as enemy warships and military aircraft when engaged in either of the following acts:
1. Taking a direct part in the hostilities on the side of the enemy 2. Acting in any capacity as a naval or military
auxiliary to the enemy’s armed forces.”); 1955 NWIP 10-2 ¶501a (“Neutral merchant vessels and aircraft acquire
enemy character and are liable to the same treatment as enemy warships and military aircraft (see paragraph 503a)
when engaging in the following acts: 1. Taking a direct part in the hostilities on the side of an enemy; 2. Acting in
any capacity as a naval or military auxiliary to an enemy’s armed forces.”).
279 See also TUCKER, THE LAW OF WAR AND NEUTRALITY AT SEA 321 (“The general principle involved is
reasonably clear, and no attempt need be made to enumerate all of the acts that may result in this assimilation to an
enemy’s armed forces. It is not the mere fact of assisting a belligerent that permits this severe treatment. Nor is it
simply the consideration that the belligerent exercises a close control and direction over the neutral merchant vessel.
The decisive consideration is rather that the services rendered are in direct support of the belligerent’s military
operations. It is this support, leading as it does to the identification of the neutral merchant vessel (or aircraft) with
the belligerent’s naval or military forces, that permits a treatment similar to that meted out to these forces.”).
280 Refer to § 13.4 (Enemy Warships).
978
by a belligerent as enemy merchant vessels or civil aircraft when engaged in either of the
following acts:281
• operating directly under enemy control, orders, charter, employment, or direction; or
• resisting an attempt to establish identity, including resisting visit and search.282
For example, such vessels and aircraft may be captured and, under certain circumstances,
destroyed.283
15.15 CAPTURE OF NEUTRAL VESSELS AND AIRCRAFT
Certain neutral merchant vessels and civil aircraft may be captured outside neutral
territory.
15.15.1 Grounds for the Capture of Neutral Vessels and Aircraft. Neutral-flagged
merchant vessels or neutral-marked civil aircraft that have acquired enemy character are liable to
capture.284 In addition, neutral merchant vessels and civil aircraft are, in general, liable to
capture by a belligerent State’s warships and military aircraft if performing any of the following
acts:285
• carrying contraband;286
281 See, e.g., 2007 NWP 1-14M ¶7.5.2 (“Neutral merchant vessels and civil aircraft acquire enemy character and
may be treated by a belligerent as enemy merchant vessels or civil aircraft when engaged in either of the following
acts:
1. Operating directly under enemy control, orders, charter, employment, or direction 2. Resisting an attempt to
establish identity, including resisting visit and search.”); 1955 NWIP 10-2 ¶501b (“Neutral merchant vessel and
aircraft acquire enemy character and are liable to the same treatment as enemy merchant vessels and aircraft (see
paragraph 503b), when engaging in the following acts: 1. Operating directly under enemy control, orders, charter,
employment, or direction; 2. Resisting an attempt to establish identity, including visit and search.”).
282 Refer to § 15.13.4.1 (Use of Force During Visit and Search).
283 Refer to § 13.5 (Enemy Merchant Vessels).
284 Refer to § 15.14 (Acquisition of Enemy Character by Neutral-Flagged Merchant Vessels and Neutral-Marked
Civil Aircraft).
285 2007 NWP 1-14M ¶7.10 (“Neutral merchant vessels and civil aircraft are liable to capture by belligerent
warships and military aircraft if engaged in any of the following activities: 1. Avoiding an attempt to establish
identity 2. Resisting visit and search 3. Carrying contraband 4. Breaching or attempting to breach blockade 5.
Presenting irregular or fraudulent papers; lacking necessary papers; or destroying, defacing, or concealing papers 6.
Violating regulations established by a belligerent within the immediate area of naval operations 7. Carrying
personnel in the military or public service of the enemy 8. Communicating information in the interest of the
enemy.”); 1955 NWIP 10-2 ¶503d (“NEUTRAL MERCHANT VESSELS AND AIRCRAFT are in general liable to capture if
performing any of the following acts: 1. Carrying contraband (see paragraph 631d). 2. Breaking, or attempting to
break, blockade (see paragraph 632g). 3. Carrying personnel in the military or public service of an enemy. 4.
Transmitting information in the interest of an enemy. 5. Avoiding an attempt to establish identity, including visit
and search. 6. Presenting irregular or fraudulent papers; lacking necessary papers; destroying, defacing, or
concealing papers. 7. Violating regulations established by a belligerent within the immediate area of naval
operations (see paragraph 430b).”).
286 Refer to § 15.12 (Neutral Commerce and Carriage of Contraband).
979
• carrying personnel in the military or public service of the enemy;287
• communicating information in the interest of the enemy;288
• breaching or attempting to breach a blockade;289
• violating regulations established by a belligerent within the immediate area of naval
operations;290
• avoiding an attempt to establish identity, including visit and search;291 or
• presenting irregular or fraudulent papers; lacking necessary papers; or destroying,
defacing, or concealing papers.292
15.15.2 Procedure for Capture and Condemnation. Belligerent States have discretion in
formulating their procedures for conducting the capture and condemnation of neutral merchant
vessels and aircraft.293 Prior exercise of the right of visit and search is not required for the
287 Cf. 1928 PAN AMERICAN MARITIME NEUTRALITY CONVENTION art. 12 (“The neutral vessel shall be seized and in
general subjected to the same treatment as enemy merchantmen: ... d) When actually and exclusively destined for
transporting enemy troops
”). Consider 1909 DECLARATION OF LONDON art. 45 (“A neutral vessel will be
condemned and will, in a general way, receive the same treatment as a neutral vessel liable to condemnation for
carriage of contraband: (1) If she is on a voyage specially undertaken with a view to the transport of individual
passengers who are embodied in the armed forces of the enemy, … . (2) If, to the knowledge of either the owner,
the charterer, or the master, she is transporting a military detachment of the enemy, or one or more persons who, in
the course of the voyage, directly assist the operations of the enemy.”).
288 Cf. 1928 PAN AMERICAN MARITIME NEUTRALITY CONVENTION art. 12 (“The neutral vessel shall be seized and in
general subjected to the same treatment as enemy merchantmen: ... d) When actually and exclusively destined ... for
the transmission of information on behalf of the enemy.”). Consider 1909 DECLARATION OF LONDON art. 45 (“A
neutral vessel will be condemned and will, in a general way, receive the same treatment as a neutral vessel liable to
condemnation for carriage of contraband: (1) If she is on a voyage especially undertaken … with a view to the
transmission of intelligence in the interest of the enemy.”).
289 Refer to § 13.10.4 (Breach and Attempted Breach of Blockade).
290 Refer to § 13.8 (Belligerent Control of the Immediate Area of Naval Operations).
291 Refer to § 15.13.4 (Procedure for Visit and Search of Merchant Vessels and Aircraft).
292 See Carrington v. Merchants’ Ins. Co., 33 U.S. 495, 521-22 (1834) (Story, J.) (“The belligerent has a right to
require a frank and bona fide conduct on the part of neutrals, in the course of their commerce in times of war; and if
the latter will make use of fraud, and false papers, to elude the just rights of the belligerents, and to cloak their own
illegal purposes, there is no injustice in applying to them the penalty of confiscation. The taint of the fraud travels
with the party and his offending instrument during the whole course of the voyage, and until the enterprise has, in
the understanding of the party himself, completely terminated. There are many analogous cases in the prize law,
where fraud is followed by similar penalties. Thus, if a neutral will cover up enemy’s property under false papers,
which also cover his own property, prize courts will not disentangle the one from the other, but condemn the whole
as good prize.”).
293 See 1928 PAN AMERICAN MARITIME NEUTRALITY CONVENTION art. 2 (“Both the detention of the vessel and its
crew for violation of neutrality shall be made in accordance with the procedure which best suits the state effecting it
and at the expense of the transgressing ship. Said state, except in the case of grave fault on its part, is not
responsible for damages which the vessel may suffer.”).
980
capture of neutral-flagged vessels or neutral-marked aircraft that have acquired enemy status, if
positive determination of status can be obtained by other means.294
Captured neutral merchant vessels and civil aircraft are sent to a port or airfield under a
belligerent State’s jurisdiction as a prize for adjudication by a prize court. Ordinarily, a
belligerent State’s warship will place a prize master and prize crew on board a captured vessel
for this purpose. Should that be impracticable, the prize may be escorted into port by a
belligerent State’s warship or military aircraft. In the latter circumstances, the prize must obey
the instructions of its escort or risk forcible measures.295
A prize may not be brought into a neutral port, except under emergency circumstances.296
A prize court cannot be set up by a belligerent on neutral territory or on a vessel in neutral
waters.297
15.15.2.1 Use of Force During Capture. Neutral vessels or aircraft attempting to
resist proper capture lay themselves open to forcible measures by a belligerent State’s warships
and military aircraft, and assume the risk of resulting damage.298 The same rule applies to
resistance during visit and search.299
15.15.3 Destruction of Neutral Prizes. Although the destruction of a neutral prize is not
absolutely forbidden, it involves a much more serious responsibility than the destruction of an
enemy prize.300 Thus, a higher standard is applicable than for the destruction of enemy prizes.301
294 1955 NWIP 10-2 ¶502a (“Historically, visit and search was considered the only legally acceptable method for
determining whether or not a merchant vessel was subject to capture. It is now recognized that changes in warfare
have rendered this method either hazardous or impracticable in many situations. In the case of enemy merchant
vessels and aircraft and neutral merchant vessels and aircraft acquiring enemy character as described in the
preceding article, the belligerent right of capture (and, exceptionally, destruction as described in paragraph 503b)
need not be preceded by visit and search, provided that a positive determination of status can be obtained by other
methods.”).
295 2007 NWP 1-14M ¶7.10 (“Captured vessels and aircraft are sent to a port or airfield under belligerent jurisdiction
as a prize for adjudication by a prize court. Ordinarily, a belligerent warship will place a prize master and prize
crew on board a captured vessel for this purpose. Should that be impracticable, the prize may be escorted into port
by a belligerent warship or military aircraft. In the latter circumstances, the prize must obey the instructions of its
escort or risk forcible measures.”); 1998 NWP 9 ¶7.10 (substantially the same).
296 Refer to § 15.9.5 (Prizes in Neutral Ports or Roadsteads).
297 HAGUE XIII art. 4 (“A Prize Court cannot be set up by a belligerent on neutral territory or on a vessel in neutral
waters.”).
298 See, e.g., 2007 NWP 1-14M ¶7.10 (“Neutral vessels or aircraft attempting to resist proper capture lay themselves
open to forcible measures by belligerent warships and military aircraft and assume all risk of resulting damage.”);
1989 NWP 9 ¶7.9 (same).
299 Refer to § 15.13.4.1 (Use of Force During Visit and Search).
300 1955 NWIP 10-2 ¶509e (“Although the destruction of a neutral prize is not absolutely forbidden, it involves a
much more serious responsibility than the destruction of an enemy prize.”).
301 Refer to § 13.5.1.3 (Destruction of Captured Enemy Merchant Vessels).
981
Every reasonable effort should be made to avoid destruction of captured neutral vessels
and aircraft.302 A capturing officer, therefore, should not order such destruction without being
entirely satisfied that the prize can neither be sent to a belligerent State port or airfield nor, in his
or her opinion, properly be released.303
Should it become necessary that the prize be destroyed, the capturing officer must
provide for the safety of the passengers and crew.304 In that event, all documents and papers
relating to the prize should be preserved. If practicable, the personal effects of passengers should
also be safeguarded.305
15.15.4 Personnel on Board Captured Neutral Vessels and Aircraft.
15.15.4.1 Officers and Crews of Captured Neutral Merchant Vessels and Civil
Aircraft. The officers and crews of captured neutral merchant vessels and civil aircraft who are
nationals of a neutral State should not be made POWs,306 even if the vessel or aircraft has
acquired the character of enemy merchant vessels or aircraft.307 However, if the vessel or
aircraft has acquired the character of an enemy warship or military aircraft,308 the officers and
crew may be held as POWs.309
302 2006 AUSTRALIAN MANUAL ¶6.59 (“Every effort should be made to avoid destruction of a captured neutral
vessel.”).
303 1955 NWIP 10-2 ¶509e (“A capturing officer, therefore, should never order such destruction without being
entirely satisfied that the military reasons therefore justify it, i.e. under circumstances such that a prize can neither be
sent in nor, in his opinion, properly released.”).
304 1928 PAN AMERICAN MARITIME NEUTRALITY CONVENTION art. 1(1) (“The ship shall not be rendered incapable
of navigation before the crew and passengers have been placed in safety.”); Treaty for the Limitation and Reduction
of Naval Armament, art. 22, Apr. 22, 1930, 46 STAT. 2858, 2881-82 (“In particular, except in the case of persistent
refusal to stop on being duly summoned, or of active resistance to visit or search, a warship, whether surface vessel
or submarine, may not sink or render incapable of navigation a merchant vessel without having first placed
passengers, crew and ship’s papers in a place of safety. For this purpose the ship's boats are not regarded as a place
of safety unless the safety of the passengers and crew is assured, in the existing sea and weather conditions, by the
proximity of land, or the presence of another vessel which is in a position to take them on board.”). Consider
Procès-Verbal Relating to the Rules of Submarine Warfare Set Forth in Part IV of the Treaty of London of April 22,
1930, Nov. 6, 1936, 173 LNTS 353, 357 (same).
305 1955 NWIP 10-2 ¶509e (“Should the necessity for the destruction of a neutral prize arise, it is the duty of the
capturing officer to provide for the safety of the passengers and crew. All documents and papers relating to a neutral
prize should be saved. If practicable, the personal effects of passengers should be saved. Every case of destruction
of a neutral prize should be reported promptly to a higher command.”).
306 1955 NWIP 10-2 ¶513a (“The officers and crews of captured neutral merchant vessels and aircraft who are
nationals of a neutral State should not be made prisoners of war.”). See also TUCKER, THE LAW OF WAR AND
NEUTRALITY AT SEA 347 (“In seizing neutral vessels the belligerent incurs certain duties that have long enjoyed the
sanction of state practice. Unless the neutral nationals serving as officers and crew of neutral vessels have taken a
direct part in the hostilities they may not be treated as prisoners of war.”).
307 Refer to § 15.14.2.2 (Acquiring the Character of an Enemy Merchant Vessel or Civil Aircraft).
308 Refer to § 15.14.2.1 (Acquiring the Character of an Enemy Warship or Military Aircraft).
309 See 2007 NWP 1-14M ¶7.10.2 (“This rule applies equally to the officers and crews of neutral vessels and aircraft
that assumed the character of enemy merchant vessels or aircraft by operating under enemy control or resisting visit
and search. If, however, the neutral vessels or aircraft had taken a direct part in the hostilities on the side of the
982
15.15.4.2 Enemy Nationals Found Onboard Neutral Merchant Vessels and Civil
Aircraft. Belligerents have a right to remove certain enemy persons from neutral vessels or
aircraft, even if there are no grounds for the capture of the vessel or aircraft as prize.310 Enemy
nationals found onboard a neutral State’s merchant vessels or civil aircraft as passengers who
are:
• a current member of an enemy military force;311
• en route to join, or be incorporated into, an enemy’s armed forces;
• employed in the public service of the enemy State; or
• engaged in, or suspected of engagement in, service in the interests of the enemy State;312
also may be interned until a determination of their status has been made.313
enemy or had served in any way as a naval or military auxiliary for the enemy, they thereby assumed the character
of enemy warships or military aircraft and, upon capture, their officers and crew may be interned as prisoners of
war.”); 1955 NWIP 10-2 ¶513a endnote 41 (“This paragraph is applicable as well to the officers and crews,
nationals of a neutral state, of captured neutral merchant vessels and aircraft which have acquired enemy character
and which are liable to the same treatment as enemy merchant vessels and aircraft, as described in paragraph 501b.
Hence, a distinction must be made between the treatment accorded to neutral merchant vessels acquiring enemy
character, and the treatment accorded to the personnel of such vessels. There is a clear exception, however, in the
case of personnel of neutral vessels and aircraft which take a direct part in the hostilities on the side of an enemy or
which serve in any way as a naval or military auxiliary for an enemy.”).
310 TUCKER, THE LAW OF WAR AND NEUTRALITY AT SEA 328 (“Despite neutral opposition during World War I to
conceding any belligerent right to remove enemy persons from neutral merchant vessels at sea, it would now seem
that—in principle—the practice of states may be regarded as having sanctioned this belligerent measure.”).
311 Consider DECLARATION OF LONDON art. 47 (“Any individual embodied in the armed forces of the enemy who is
found on board a neutral merchant vessel, may be made a prisoner of war, even though there be no ground for the
capture of the vessel.”).
312 CDR Joe Munster, Removal of Persons from Neutral Shipping, THE JAG JOURNAL: THE OFFICE OF THE JUDGE
ADVOCATE JOURNAL OF THE NAVY 3, 18 (Oct. 1952) (“It appears unlikely that the old rules concerning the removal
of persons from neutral shipping can much longer survive, even extended to include reservists. With the increasing
development of science it would appear foolhardly for a nation to permit an Oppenheimer, a Millikan, a Fermi, an
Einstein, or any accomplished atomic or neuclear [sic] physicist to return to his own country, if that country be an
opposing belligerent. An expert in guided missiles would be more important to a belligerent country than an
ordinary soldier; and notwithstanding the expert is not ‘embodied in the armed services’ it would appear that the
rules and regulations of international law must be amended to bring them into line with the requirements of
belligerent necessity. It does not appear that neutrals can properly maintain that no persons other than those
connected with the military, either entirely or in a reserve status, may be removed from neutral shipping.”).
313 2007 NWP 1-14M ¶7.10.2 (“Enemy nationals found on board neutral merchant vessels and civil aircraft as
passengers who are actually embodied in the military forces of the enemy, who are en route to serve in the enemy’s
armed forces, who are employed in the public service of the enemy, or who may be engaged in or suspected of
service in the interests of the enemy may be made prisoners of war. All such enemy nationals may be removed from
the neutral vessel or aircraft whether or not there is reason for its capture as a neutral prize.”); 1955 NWIP 10-2
¶513b (“Enemy nationals found on board neutral merchant vessels and aircraft as passengers who are actually
embodied in the military forces of an enemy, or who are en route to serve in an enemy’s military forces, or who are
employed in the public service of an enemy, or who may be engaged in or suspected of service in the interests of an
enemy may be made prisoners of war.”).
983
15.16 BELLIGERENT FORCES TAKING REFUGE IN NEUTRAL TERRITORY
Neutral States have rights and duties with respect to the treatment of belligerent State
forces that enter, or seek to enter, their territory. Generally, a neutral State is required to intern a
belligerent State’s forces to ensure that they do not return to the armed conflict.314
15.16.1 Discretion of the Neutral State in Offering Asylum to Belligerent Forces Seeking
Refuge. A neutral State has discretion in whether to permit belligerent forces seeking refuge to
enter its territory.
15.16.1.1 Neutral Right to Deny Access or to Impose Conditions on Belligerent
Forces. A neutral State is not bound to permit a belligerent State’s forces to enter its territory.315
The neutral State may impose conditions on belligerent forces seeking refuge in its territory.316
In cases of large bodies of belligerent forces seeking refuge in neutral territory, these conditions
will usually be stipulated in an agreement concluded by the representatives of the neutral State
and the senior officer of the forces.317
15.16.1.2 Neutral Duty to Disarm and Intern the Belligerent Forces. If the
belligerent forces are permitted to seek refuge in neutral territory, the neutral State must take
appropriate measures to ensure that these forces will no longer participate in the armed conflict.
314 For example, I REPORT OF THE INTERNATIONAL COMMITTEE OF THE RED CROSS ON ITS ACTIVITIES DURING THE
SECOND WORLD WAR (SEPTEMBER 1, 1939 - JUNE 30, 1947) 557 (1948) (“Neutral States. - The Swiss Government
agreed, in June 1940, to receive on their territory and to intern 32,000 men of the 45th French Army Corps and
13,000 men of the 2nd Polish Division. After the repatriation of the French internees in January 1941, the Polish
Division remained, and in 1943, the authorities interned 23,000 men of the Italian forces. In addition, individual
internments during hostilities amounted to 7,000 combatants belonging to 37 different nationalities. In September
1939, Rumania received 20,000 men of the Polish forces, who were interned. Hungary received 36,000, Lithuania
14,000 and Latvia 1,600. Other neutral countries gave refuge to a limited number of military internees of various
nationalities.”); Ex parte Toscano, 208 F. 938, 939 (S.D. CA 1913) (“That for several days prior to April 13, 1913,
an armed force of the Constitutionalist army attacked the same town of Naco, and on April 13, 1913, the petitioners
and other Federalist troops occupying the said town were defeated and driven out of said town of Naco, and were
pursued by the victorious Constitutionalist troops, and to avoid surrendering to the Constitutionalist force, the
Federalist troops fled with their arms across the boundary line between the United States and Mexico, and sought
refuge and asylum from the pursuing enemy in the United States. That immediately upon crossing the said neutral
boundary and reaching United States soil, the said petitioners and other Federalist troops belonging to said
belligerent army voluntarily surrendered themselves to the armed forces of the United States, which said armed
forces of the United States, acting under authority of the President of the United States, thereupon disarmed said
belligerent troops and detained and interned them pending the removal of said belligerent troops to a point within
the territory of the United States at a distance from the theater of said civil war.”).
315 1956 FM 27-10 (Change No. 1 1976) ¶533 (“A neutral is not bound to permit belligerent troops to enter its
territory.”).
316 1956 FM 27-10 (Change No. 1 1976) ¶534 (“If troops or soldiers of a belligerent are permitted to seek refuge in
neutral territory, the neutral is authorized to impose the terms upon which they may do so.”).
317 1956 FM 27-10 (Change No. 1 1976) ¶534 (“In cases of large bodies of troops seeking refuge in neutral territory,
these conditions will usually be stipulated in a convention drawn up by the representatives of the neutral power and
the senior officer of the troops.”).
984
If such measures were not taken, then the neutral State’s territory might serve as an unlawful
sanctuary or base of operations for the belligerent.318
Thus, belligerent forces received in neutral territory must be disarmed, and appropriate
measures must be taken to prevent their leaving the neutral State.319 In particular, a neutral State
that receives on its territory personnel belonging to the belligerent forces shall intern them, as far
as possible, at a distance from the theater of war.320 For example, if belligerent military aircraft
land in a neutral State, that State must intern the aircraft, aircrew, and accompanying military
personnel for the duration of the war.321
15.16.2 Neutral Reception of the Wounded, Sick, and Shipwrecked. Like other
belligerent personnel received in neutral land territory, the wounded, sick, and shipwrecked who
are received within a neutral jurisdiction are also generally to be guarded so that they can no
longer participate in hostilities.
However, ground transports of belligerent wounded and sick personnel may be
authorized to pass through neutral land territory by special agreement.322
15.16.2.1 Wounded, Sick, and Shipwrecked Landed in Neutral Ports. Wounded,
sick, or shipwrecked persons who are landed in neutral ports with the consent of the local
authorities shall, failing arrangements to the contrary between the neutral State and the
belligerent States, be so guarded by the neutral State, where so required by international law, that
such persons cannot again take part in operations of war.323
The costs of hospital accommodation and internment shall be borne by the belligerent
State on whom the wounded, sick, or shipwrecked persons depend.324
15.16.2.2 Wounded, Sick, and Shipwrecked Taken Aboard a Neutral State’s
Warship or Aircraft. If wounded, sick, or shipwrecked persons are taken on board a neutral
318 Refer to § 15.5 (Prohibition on the Use of Neutral Territory as a Base of Operations).
319 1956 FM 27-10 (Change No. 1 1976) ¶533 (“On the other hand, it may permit them to do so without violating its
neutrality, but the troops must be interned or confined in places designated by the neutral. They must be disarmed
and appropriate measures must be taken to prevent their leaving the neutral country.”).
320 HAGUE V art. 11 (“A neutral Power which receives on its territory troops belonging to the belligerent armies shall
intern them, as far as possible, at a distance from the theatre of war.”).
321 FINAL REPORT ON THE PERSIAN GULF WAR 627 (“Under Article 11 of Hague V and traditional law of war
principles regarding neutral rights and obligations, when belligerent military aircraft land in a nation not party to a
conflict, the neutral must intern the aircraft, aircrew, and accompanying military personnel for the duration of the
war.”).
322 Refer to § 15.18.1 (Authorized Ground Transports of Wounded and Sick Combatants Through Neutral Territory).
323 GWS-SEA art. 17 (“Wounded, sick or shipwrecked persons who are landed in neutral ports with the consent of
the local authorities, shall, failing arrangements to the contrary between the neutral and the belligerent Powers, be so
guarded by the neutral Power, where so required by international law, that the said persons cannot again take part in
operations of war.”).
324 GWS-SEA art. 17 (“The costs of hospital accommodation and internment shall be borne by the Power on whom
the wounded, sick or shipwrecked persons depend.”).
985
State’s warship or a neutral State’s military aircraft, it shall be ensured, where so required by
international law, that they can take no further part in operations of war.325
15.16.2.3 Wounded and Sick Disembarked From Belligerent Medical Aircraft.
Unless otherwise agreed between the neutral State and the belligerent States, the wounded and
sick who are disembarked, with the consent of the local authorities, on neutral territory by
medical aircraft, shall be detained by the neutral State, where so required by international law, in
such a manner that they cannot again take part in military operations.326
The cost of their accommodation and internment shall be borne by the State on which
they depend.327
15.16.3 Conditions of Internment in a Neutral State. The neutral State may keep
belligerent forces in camps and even confine them in military compounds or in places set apart
for the purpose of internment.328 Belligerent forces should be interned, as far as possible, at a
distance from the theater of war.329
15.16.3.1 Provision of POW Treatment and Application of the GWS and GWS-
Sea by Analogy. Under Article 4B(2) of the GPW, persons who are entitled to POW status if
they fall into the power of the enemy during international armed conflict are generally entitled to
POW treatment, as a minimum, if they are interned by a neutral State under its duties under
international law.330
325 GWS-SEA art. 15 (“If wounded, sick, or shipwrecked persons are taken on board a neutral warship or a neutral
military aircraft, it shall be ensured, where so required by international law, that they can take no further part in
operations of war.”).
326 GWS art. 37 (“Unless otherwise agreed between the neutral Power and the Parties to the conflict, the wounded
and sick who are disembarked, with the consent of the local authorities, on neutral territory by medical aircraft, shall
be detained by the neutral Power, where so required by international law, in such a manner that they cannot again
take part in operations of war.”); GWS-SEA art. 40 (same).
327 GWS art. 37 (“The cost of their accommodation and internment shall be borne by the Power on which they
depend.”); GWS-SEA art. 40 (same).
328 HAGUE V art. 11 (“It may keep them in camps and even confine them in fortresses or in places set apart for this
purpose.”).
329 HAGUE V art. 11 (“A neutral Power which receives on its territory troops belonging to the belligerent armies shall
intern them, as far as possible, at a distance from the theatre of war.”). Refer to § 9.11.4.1 (Avoidance of the
Combat Zone); § 9.11.3 (Location of POW Camps).
330 GPW art. 4B (“The following shall likewise be treated as prisoners of war under the present Convention: … (2)
The persons belonging to one of the categories enumerated in the present Article, who have been received by neutral
or non-belligerent Powers on their territory and whom these Powers are required to intern under international law,
without prejudice to any more favourable treatment which these Powers may choose to give and with the exception
of Articles 8, 10, 15, 30, fifth paragraph, 58-67, 92, 126 and, where diplomatic relations exist between the Parties to
the conflict and the neutral or non-belligerent Power concerned, those Articles concerning the Protecting Power.
Where such diplomatic relations exist, the Parties to a conflict on whom these persons depend shall be allowed to
perform towards them the functions of a Protecting Power as provided in the present Convention, without prejudice
to the functions which these Parties normally exercise in conformity with diplomatic and consular usage and
treaties.”). Refer to § 9.3.3 (Persons Entitled to POW Treatment).
986
Provisions of the GWS and GWS-Sea apply by analogy to wounded and sick, to
members of the medical personnel, and to chaplains of the armed forces of the parties to the
conflict, who are received or interned in neutral territory, as well as to deceased persons of a
State that is a party to a conflict found there.331
15.16.3.2 Belligerent State Acting as the Protecting Power. Where diplomatic
relations exist between the parties to the conflict and the neutral or non-belligerent Power
concerned, the parties to a conflict on whom these persons depend shall be allowed to perform
towards them the functions of a Protecting Power as provided in the GPW, without prejudice to
the functions that these parties normally exercise in conformity with diplomatic and consular
usage and treaties.332
15.16.3.3 Reimbursement of Expenses at the Conclusion of Peace. In the absence
of a special convention to the contrary, the neutral Power shall supply the interned with the food,
clothing, and relief required by humanity.333 At the conclusion of peace, the neutral Power’s
expenses incurred supporting the internment shall be made good.334
The provisions of the GPW regarding the costs of POW internment and the financial
resources of POWs are not applicable to the situation of persons treated as POWs who have been
interned by a neutral State.335
331 GWS art. 4 (“Neutral Powers shall apply by analogy the provisions of the present Convention to the wounded
and sick, and to members of the medical personnel, and to chaplains of the armed forces of the Parties to the
conflict, received or interned in their territory, as well as to dead persons found.”); GWS-SEA art. 5 (“Neutral
Powers shall apply by analogy the provisions of the present Convention to the wounded, sick and shipwrecked, and
to members of the medical personnel and to chaplains of the armed forces of the Parties to the conflict received or
interned in their territory, as well as to dead persons found.”).
332 GPW art. 4B(2) (“Where such diplomatic relations exist, the Parties to a conflict on whom these persons depend
shall be allowed to perform towards them the functions of a Protecting Power as provided in the present Convention,
without prejudice to the functions which these Parties normally exercise in conformity with diplomatic and consular
usage and treaties.”).
333 HAGUE V art. 12 (“In the absence of a special convention to the contrary, the neutral Power shall supply the
interned with the food, clothing, and relief required by humanity. At the conclusion of peace the expenses caused by
the internment shall be made good.”).
334 For example, A. PEARCE HIGGINS, THE HAGUE PEACE CONFERENCES AND OTHER INTERNATIONAL CONFERENCES
CONCERNING THE LAWS AND USAGES OF WAR: TEXTS OF CONVENTIONS WITH COMMENTARIES 293 footnote 2
(1909) (“The most striking example of internment occurred in 1871 during the Franco-Prussian war when over
80,000 French troops under General Clinchant entered Swiss territory and were interned for the remainder of the
war; France at the conclusion of the war paid to Switzerland some 11 million francs for their maintenance.”).
335 See GPW art. 4B (“The following shall likewise be treated as prisoners of war under the present Convention: …
(2) The persons belonging to one of the categories enumerated in the present Article, who have been received by
neutral or non-belligerent Powers on their territory and whom these Powers are required to intern under international
law, without prejudice to any more favourable treatment which these Powers may choose to give and with the
exception of Articles 8, 10, 15, 30, fifth paragraph, 58-67, 92, 126 and, where diplomatic relations exist between the
Parties to the conflict and the neutral or non-belligerent Power concerned, those Articles concerning the Protecting
Power.”) (emphasis added).
987
15.16.4 Parole of Belligerent Personnel Interned in Neutral Territory. The neutral State
shall decide whether interned officers can be left at liberty on giving their parole not to leave the
neutral territory without permission.336
Neutral States may release enlisted personnel on parole, prescribe penalties for violations
of parole, and authorize personnel to depart neutral territory temporarily so long as these actions
remain consistent with its obligations as a neutral State.337 The granting of leave to an interned
officer to return to his or her own country, however, would be considered an exceptional
measure, and a neutral State inclined to grant such permission would be prudent in the first
instance to obtain the consent of the opposing belligerent State.
A neutral State may demand the return of persons who have been released on parole but
have left the neutral State in violation of their parole.338 If such persons return to the State in
whose armed forces they serve, that State is obliged to return them to the neutral State at its
request.339
15.16.5 Military Equipment and Supplies of Belligerent Forces Taking Refuge. The
munitions, arms, vehicles, equipment, and other supplies that the interned forces are allowed to
bring with them into a neutral State are likewise detained by the neutral State. A belligerent
State’s military equipment and supplies, whether its own or captured, which are brought on to
neutral territory must be returned at the end of the armed conflict to the State to which the items
336 HAGUE V art. 11 (“It shall decide whether officers can be left at liberty on giving their parole not to leave the
neutral territory without permission.”).
337 Cf. JAMES BROWN SCOTT, THE PROCEEDINGS OF THE HAGUE PEACE CONFERENCES: I THE CONFERENCE OF 1907
147-48 (1920) (“Article 57, paragraph 3, of the [1899 Hague] Regulations leaves it to the neutral State to decide
whether interned officers may be left at liberty on giving their parole not to leave the neutral territory without
permission. It does not say upon what conditions a permission to leave this territory should be predicated; neither
does it provide any penalty for violation of the parole. Finally, it does not mention either non-commissioned
officers or private soldiers. The Japanese delegation proposed to fill this gap by deciding:
(1) that the interned men,
without distinction of rank, cannot be liberated nor permitted to reenter their country except with the consent of the
adverse party under conditions fixed by it; (2) that the parole given in such cases to the neutral State would be
equivalent to a parole given to the adverse party. Without ignoring the merits of this proposal, the Commission
preferred to continue the existing text of the Regulations. It considered that permission given to an interned man to
return temporarily to his country is something too exceptional to require regulation in express terms. There was no
difficulty, moreover, in recognizing that the Japanese proposal conforms to recent precedents and contains a useful
hint for a neutral State desirous of remaining entirely free from responsibility.”).
338 For example, Robert Lansing, The Secretary of State to the German Ambassador, Nov. 16, 1915, reprinted in
JAMES BROWN SCOTT, DIPLOMATIC CORRESPONDENCE BETWEEN THE UNITED STATES AND GERMANY AUGUST 1,
1914 - APRIL 6, 1917, 163 (1918) (“It will be recalled that during the Russo-Japanese War, when the Russian Ship
Lena was interned by the United States Authorities on the Pacific coast, three officers of that ship escaped and
returned to Russia; and that upon the Government of the United States calling the matter to the attention of the
Russian Government it immediately caused the escaped officers to return to American jurisdiction where they were
interned for the remainder of the war. This precedent this Government regards as in accord with the best practice of
nations and applicable to the cases which I have had the honor to present in this note.”).
339 1956 FM 27-10 (Change No. 1 1976) ¶535 (“Officers and men interned in a neutral State may in the discretion of
that State be released on their parole under conditions to be prescribed by the neutral State. If such persons leave the
neutral State in violation of their parole, the State in whose armed forces they serve is obliged to return them to the
neutral State at its request.”).
988
belong. Similarly, captured war material found in the possession of the belligerent forces that
take refuge on neutral territory is the property of their State, regardless of its origin.340
15.16.6 Retention of Medical Personnel and Chaplains in a Neutral State. Medical and
religious personnel serving with belligerent forces that are interned in neutral territory may be
retained only in so far as the health and the numbers of such forces so require.341 Subject to
these requirements, they must be returned as soon as possible to the State to which they
belong.342 Chaplains are in the same position, their retention being dependent upon the spiritual
needs of the interned forces.343 Medical personnel and chaplains who are retained must be
accorded similar treatment to those retained under the GPW.344
15.17 POWS OR INTERNEES BROUGHT TO, OR RECEIVED BY, A NEUTRAL STATE
15.17.1 Escaped POWs Received by a Neutral State. POWs who have escaped to neutral
territory are deemed to have successfully escaped from the Detaining Power.345
A neutral State may deny the admission of escaped POWs or receive them. A neutral
State that receives escaped POWs shall leave them at liberty. If it allows them to remain in its
territory, it may assign them a place of residence.346
15.17.2 POWs Brought Into a Neutral State by Belligerent Forces Taking Refuge. POWs
brought into a neutral State by belligerent forces that take refuge in the neutral State are treated
like POWs who have escaped to neutral territory.347 This means that the POWs regain their
340 See JAMES BROWN SCOTT, THE PROCEEDINGS OF THE HAGUE PEACE CONFERENCES: I THE CONFERENCE OF 1907
145 (1920) (“What becomes of the war material captured by troops and brought with them into the territory of a
neutral State? This question was put by the Dutch delegation, which made the following motion: ‘War material
captured from the enemy by an armed force and brought with it while taking refuge on neutral territory shall be
restored by the Government thereof to the State from which it was taken after the conclusion of peace.’ But the
Netherland delegation did not insist on its motion in the face of the objection made to it. On the one hand, the case
of war material captured from the enemy cannot be assimilated to the case of prisoners of war. The capture of
matériel creates for the captor an immediate right of ownership, which places this matériel on the same footing as
the captor’s own matériel. On the other hand, even if the captor’s right to the property should become uncertain,
owing to his taking refuge in the neutral territory, there would be no reason for making the neutral State the judge of
the question and for imposing on it the invidious duty of examining the matériel brought into its territory by a
belligerent force to see what has been taken from the enemy and what belongs to the force under some other title.”).
341 Refer to § 7.9.1.2 (Medical and Religious Personnel Who May Be Retained).
342 Refer to § 7.9.4 (Return of Personnel Whose Retention Is Not Indispensable).
343 Refer to § 4.9.1.3 (Chaplains Attached to the Armed Forces).
344 Refer to § 7.9.5 (Rights and Privileges of Retained Personnel).
345 Refer to § 9.25.1.1 (Types of Successful Escapes).
346 HAGUE V art. 13 (“A neutral Power which receives escaped prisoners of war shall leave them at liberty. If it
allows them to remain in its territory it may assign them a place of residence.”).
347 HAGUE V art. 13 (“A neutral Power which receives escaped prisoners of war shall leave them at liberty. If it
allows them to remain in its territory it may assign them a place of residence. The same rule applies to prisoners of
war brought by troops taking refuge in the territory of a neutral Power.”).
989
liberty from the belligerent forces that previously held them captive, and that if the neutral State
allows them to remain on its territory, it may assign them a place of residence.
POWs brought into a neutral State by belligerent forces taking refuge are released from
their captivity by the belligerent forces that previously held them because of a concern that the
detention operations by the belligerent forces would constitute a form of continuation of
hostilities on neutral territory and because the POWs probably would have been freed had the
belligerent forces not taken refuge in neutral territory.348
15.17.3 POWs Brought to a Neutral State by Special Agreement Among the Neutral State
and the Parties to a Conflict. POWs may be brought to a neutral State for internment by a special
agreement among the neutral State and the parties to the conflict.349 Wounded and sick POWs
may also be brought to neutral countries for accommodation by a special agreement among the
neutral State and the parties to the conflict.350
Such special agreements must not adversely affect the situation of POWs, nor restrict the
rights that the GPW confers upon them.351
15.17.4 Certain Classes of Protected Persons Brought to a Neutral State by Special
Agreement Among the Neutral State and the Parties to a Conflict. Certain classes of civilian
internees may be brought to a neutral State for internment by a special agreement among the
neutral State and the parties to the conflict.352 Agreements may also be concluded for children
under the age of fifteen who are orphaned or separated from their families to stay in neutral
countries.353
348 See JAMES BROWN SCOTT, THE PROCEEDINGS OF THE HAGUE PEACE CONFERENCES: I THE CONFERENCE OF 1907
144 (1920) (“Ought prisoners of war brought into the territory of a neutral State by belligerent troops who take
refuge there, to become free, or should they be interned like the troops? Upon the motion of the Netherland
delegation the Commission declared for the first solution. The only obstacle to the freedom of the prisoners here
referred to lies in the actual power that the belligerent forces which captured them are exercising over them, and this
actual power vanishes the moment the captor takes refuge in the territory of a neutral State. Moreover, troops taking
this extreme step, do so in order to escape from an enemy who is pressing them, and from a capitulation whose
effect would of course be to free the prisoners in their power.”); Caleb Cushing, Attorney General, Belligerent
Asylum, Apr. 28, 1855, 7 OPINIONS OF THE ATTORNEY GENERAL 122, 131 (1856) (“From all these premises, the
consequences are inevitable in regard to the prisoners on board the Sitka. So long as they remained on board that
ship, they were in the territory and jurisdiction of her sovereign. There, the neutral has no right to meddle with
them. If, indeed, they be landed, then they pass from the jurisdiction of the belligerent to that of the neutral; they
become practically free, because their detention is forcible, and force cannot be exercised on the neutral territory;”).
349 Refer to § 9.36.3 (Agreements to Intern POWs in Neutral Territory).
350 Refer to § 9.36.2 (Accommodation in Neutral Countries).
351 Refer to § 9.1.2.2 (Special Agreements Under the GPW).
352 Refer to § 10.9.6 (Agreements for the Release, Return, or Accommodation in a Neutral Country of Certain
Classes of Internees).
353 Refer to § 4.20.1.1 (Children Under Fifteen Who Are Orphaned or Separated).
990
Such special agreements must not adversely affect the situation of protected persons nor
restrict the rights that the GC confers upon them.354
15.18 AUTHORIZED PASSAGE OF WOUNDED AND SICK COMBATANTS THROUGH NEUTRAL
TERRITORY
Ground transports of wounded and sick combatants may pass through a neutral State’s
land territory with the permission of the neutral State. Subject to rules established by the neutral
State, medical aircraft of belligerent States may fly over the territory of neutral States, land on it
in case of necessity, or use it as a port of call.
15.18.1 Authorized Ground Transports of Wounded and Sick Combatants Through
Neutral Territory. A neutral State may authorize the passage into its territory of wounded or sick
persons belonging to belligerent forces, on condition that such transports shall carry neither
personnel nor material of war.355 In such a case, the neutral Power is bound to take whatever
measures of safety and control are necessary for the purpose.356
However, if any such persons are committed to the care of the neutral State or remain in
the neutral State’s territory, they must be guarded so as to ensure they do not take part again in
the war.357
15.18.1.1 Discretion of the Neutral State to Authorize Such Passage. The neutral
State has the right, but not the obligation, to permit such passage; if provided, such passage
should be provided on an impartial basis to all belligerent States.358
It is not necessary to obtain the consent of the other belligerent States before permitting
the passage of sick and wounded personnel, but it would be advisable to do so if considerable
numbers are involved.359
354 Refer to § 10.1.1.2 (Special Agreements Under the GC).
355 HAGUE V art. 14 (“A neutral Power may authorize the passage into its territory of wounded or sick belonging to
the belligerent armies, on condition that the trains bringing them shall carry neither personnel or material of war.”).
356 HAGUE V art. 14 (“In such a case, the neutral Power is bound to take whatever measures of safety and control are
necessary for the purpose.”).
357 Refer to § 15.16.1.2 (Neutral Duty to Disarm and Intern the Belligerent Forces).
358 1956 FM 27-10 (Change No. 1 1976) ¶541 (“The neutral power is under no obligation to permit the passage of a
convoy of sick and wounded through its territory, but when such a convoy is permitted to pass, the neutral must
exercise control, must see that neither personnel nor material other than that necessary for the care of the sick and
wounded is carried, and generally must accord impartiality of treatment to the belligerents.”); 2004 UK MANUAL
¶8.162 (“It is under no obligation to do so but if the privilege is accorded, it must be given to all belligerent states
impartially.”).
359 For example, 2004 UK MANUAL ¶8.162.1 footnote 427 (“After the battle of Sedan in the Franco-German war of
1870-71, the German General Staff wished to send railway trains conveying wounded to Germany through Belgium
and Luxembourg. The French Minister of War protested. He argued, rightly, that this would free lines to bring
forward fresh soldiers and ammunition. Belgium, after consulting the British government, decided that, if one of the
belligerents objected, the giving of permission would be a breach of neutrality, and therefore refused it.
991
15.18.1.2 Personnel or Material of War Accompanying the Wounded or Sick. A
neutral State permitting the passage of sick and wounded into and through its territory must take
measures of safety and control to ensure that combatants or military supplies do not accompany
them. If combatants accompany the passage of the wounded and sick, they should be
interned.360 Similarly, any military supplies must be seized and placed in safe custody until the
end of the conflict.361
Medical personnel and materials necessary for the care of the wounded and sick of a
convoy of evacuation may be permitted to accompany the convoy.362
15.18.1.3 Wounded and Sick POWs Brought Into Neutral Territory Under
Authorized Ground Transports. Wounded and sick POWs brought by one of the belligerents as
part of a convoy of evacuation that is granted passage through neutral territory, and belonging to
the hostile party, must be guarded by the neutral State so as to ensure they do not take part again
in the operations of the war.363
Thus, wounded and sick and POWs brought into neutral territory by the Detaining Power
as part of a convoy of evacuation granted right of passage through neutral territory are not treated
like escaping POWs or POWs brought by belligerent forces seeking asylum in neutral territory
(i.e., transported to their own country or liberated).364 Instead, they are treated like other
wounded, sick, and shipwrecked combatants who are received within neutral territory, and they
must be guarded by the neutral State.365
15.18.1.4 Wounded and Sick Combatants Committed to the Care of the Neutral
State. Wounded and sick combatants brought under these conditions into neutral territory by one
of the belligerents, and who do not simply pass through neutral territory but are committed to the
Luxembourg took the opposite view and granted it. Under international law, Luxembourg was correct in its
reasoning but, in view of the cogent arguments put forward by France, Belgium was right in its decision.”).
360 Refer to § 15.16.1.2 (Neutral Duty to Disarm and Intern the Belligerent Forces).
361 Refer to § 15.16.5 (Military Equipment and Supplies of Belligerent Forces Taking Refuge).
362 1956 FM 27-10 (Change No. 1 1976) ¶545 (“Medical personnel and materials necessary for the care of the sick
and wounded of a convoy of evacuation, permitted to pass through neutral territory under Article 14, H. V (par.
539), may be permitted to accompany the convoy.”).
363 HAGUE V art. 14 (“The wounded and sick brought under these conditions into neutral territory by one of the
belligerents, and belonging to the hostile party, must be guarded by the neutral Power so as to ensure their not taking
part again in the operations of the war.”).
364 1956 FM 27-10 (Change No. 1 1976) ¶543 (“Sick and wounded prisoners of war brought into neutral territory by
the Detaining Power as part of a convoy of evacuation granted right of passage through neutral territory may not be
transported to their own country or liberated, as are prisoners of war escaping into, or brought by troops seeking
asylum in neutral territory, but must be detained by the neutral power, subject to the provisions contained in
paragraphs 188 through 196.”).
365 Refer to § 15.16.2 (Neutral Reception of the Wounded, Sick, and Shipwrecked).
992
care of the neutral State, must be guarded by the neutral State so as to ensure they do not take
part again in the operations of the war.366
15.18.2 Medical Aircraft and Neutral Territory. Subject to conditions and restrictions
established by the neutral State, medical aircraft of belligerent States may fly over the territory of
neutral States, land on it in case of necessity, or use it as a port of call.367 Belligerent States shall
give the neutral States previous notice of their passage over the neutral State and obey all
summons to alight, on land or water.368
The neutral State may place conditions or restrictions on the passage or landing of
medical aircraft on its territory.369 Such conditions or restrictions shall be applied equally to all
belligerent States.370 Belligerent States’ medical aircraft would be immune from attack only
when flying on routes, at heights, and at times specifically agreed upon between the belligerent
States and the neutral State concerned.371
As a general matter, the wounded and sick who are disembarked, with the consent of the
local authorities, on neutral territory by medical aircraft, shall be detained by the neutral State,
where so required by international law, in such a manner that they cannot again take part in
military operations.372
366 HAGUE V art. 14 (“The wounded and sick brought under these conditions into neutral territory by one of the
belligerents, and belonging to the hostile party, must be guarded by the neutral Power so as to ensure their not taking
part again in the operations of the war. The same duty shall devolve on the neutral State with regard to wounded or
sick of the other army who may be committed to its care.”).
367 GWS art. 37 (“Subject to the provisions of the second paragraph, medical aircraft of Parties to the conflict may
fly over the territory of neutral Powers, land on it in case of necessity, or use it as a port of call.”); GWS-SEA art. 40
(same).
368 GWS art. 37 (“They shall give the neutral Powers previous notice of their passage over the said territory and
obey all summons to alight, on land or water.”); GWS-SEA art. 40 (same).
369 GWS art. 37 (“The neutral Powers may, however, place conditions or restrictions on the passage or landing of
medical aircraft on their territory.”); GWS-SEA art. 40 (same).
370 GWS art. 37 (“Such possible conditions or restrictions shall be applied equally to all Parties to the conflict.”);
GWS-SEA art. 40 (same).
371 GWS art. 37 (“They will be immune from attack only when flying on routes, at heights and at times specifically
agreed upon between the Parties to the conflict and the neutral Power concerned.”); GWS-SEA art. 40 (same).
372 Refer to § 15.16.2.3 (Wounded and Sick Disembarked From Belligerent Medical Aircraft).
993
XVI - Cyber Operations
Chapter Contents
16.1 Introduction
16.2 Application of the Law of War to Cyber Operations
16.3 Cyber Operations and Jus ad Bellum
16.4 Cyber Operations and the Law of Neutrality
16.5 Cyber Operations and Jus in Bello
16.6 Legal Review of Weapons That Employ Cyber Capabilities
16.1 INTRODUCTION
This Chapter addresses the law of war and cyber operations. It addresses how law of war
principles and rules apply to relatively novel cyber capabilities and the cyber domain.
As a matter of U.S. policy, the United States has sought to work internationally to clarify
how existing international law and norms, including law of war principles, apply to cyber
operations.1
Precisely how the law of war applies to cyber operations is not well-settled, and aspects
of the law in this area are likely to continue to develop, especially as new cyber capabilities are
developed and States determine their views in response to such developments.2
1 See, e.g., United States Submission to the U.N. Group of Governmental Experts on Developments in the Field of
Information and Telecommunications in the Context of International Security (2014-15), 1 (“But the challenge is
not whether existing international law applies to State behavior in cyberspace. As the 2012-13 GGE affirmed,
international law does apply, and such law is essential to regulating State conduct in this domain. The challenge is
providing decision-makers with considerations that may be taken into account when determining how existing
international law applies to cyber activities. Despite this challenge, history has shown that States, through
consultation and cooperation, have repeatedly and successfully applied existing bodies of law to new technologies.
It continues to be the U.S. view that all States will benefit from a stable international ICT [information and
communication technologies] environment in which existing international law is the foundation for responsible State
behavior in cyberspace.”); Barack Obama, International Strategy for Cyberspace: Prosperity, Security, and
Openness in a Networked World, 9 (May 2011) (“The development of norms for state conduct in cyberspace does
not require a reinvention of customary international law, nor does it render existing international norms obsolete.
Long-standing international norms guiding state behavior—in times of peace and conflict—also apply in
cyberspace. Nonetheless, unique attributes of networked technology require additional work to clarify how these
norms apply and what additional understandings might be necessary to supplement them. We will continue to work
internationally to forge consensus regarding how norms of behavior apply to cyberspace, with the understanding that
an important first step in such efforts is applying the broad expectations of peaceful and just interstate conduct to
cyberspace.”); DEPARTMENT OF DEFENSE, Department of Defense Cyberspace Policy Report: A Report to Congress
Pursuant to the National Defense Authorization Act for Fiscal Year 2011, Section 934, 7-8 (Nov. 2011) (“The
United States is actively engaged in the continuing development of norms of responsible state behavior in
cyberspace, making clear that as a matter of U.S. policy, long-standing international norms guiding state behavior
also apply equally in cyberspace. Among these, applying the tenets of the law of armed conflict are critical to this
vision, although cyberspace’s unique aspects may require clarifications in certain areas.”).
2 Department of Defense, Office of the General Counsel, An Assessment of International Legal Issues in Information
Operations (2nd ed., Nov. 1999), reprinted in 76 U.S. NAVAL WAR COLLEGE INTERNATIONAL LAW STUDIES 459,
994
16.1.1 Cyberspace as a Domain. As a doctrinal matter, DoD has recognized cyberspace
as an operational domain in which the armed forces must be able to defend and operate, just like
the land, sea, air, and space domains.3
Cyberspace may be defined as “[a] global domain within the information environment
consisting of interdependent networks of information technology infrastructures and resident
data, including the Internet, telecommunications networks, computer systems, and embedded
processors and controllers.”4
16.1.2 Description of Cyber Operations. Cyberspace operations may be understood to be
those operations that involve “[t]he employment of cyberspace capabilities where the primary
purpose is to achieve objectives in or through cyberspace.”5 Cyber operations: (1) use cyber
capabilities, such as computers, software tools, or networks; and (2) have a primary purpose of
achieving objectives or effects in or through cyberspace.
16.1.2.1 Examples of Cyber Operations. Cyber operations include those
operations that use computers to disrupt, deny, degrade, or destroy information resident in
computers and computer networks, or the computers and networks themselves. Cyber operations
can be a form of advance force operations, which precede the main effort in an objective area in
order to prepare the objective for the main assault. For example, cyber operations may include
reconnaissance (e.g., mapping a network), seizure of supporting positions (e.g., securing access
to key network systems or nodes), and pre-emplacement of capabilities or weapons (e.g.,
implanting cyber access tools or malicious code). In addition, cyber operations may be a method
of acquiring foreign intelligence unrelated to specific military objectives, such as understanding
464-65 (2002) (“The international community ordinarily does not negotiate treaties to deal with problems until their
consequences have begun to be felt. This is not all bad, since the solution can be tailored to the actual problems that
have occurred, rather than to a range of hypothetical possibilities. One consequence, however, is that the resulting
law, whether domestic or international, may be sharply influenced by the nature of the events that precipitate legal
developments, together with all their attendant policy and political considerations. … Similarly, we can make some
educated guesses as to how the international legal system will respond to information operations, but the direction
that response actually ends up taking may depend a great deal on the nature of the events that draw the nations’
attention to the issue. If information operations techniques are seen as just another new technology that does not
greatly threaten the nations’ interests, no dramatic legal developments may occur. If they are seen as a revolutionary
threat to the security of nations and the welfare of their citizens, it will be much more likely that efforts will be made
to restrict or prohibit information operations by legal means. These are considerations that national leaders should
understand in making decisions on using information operations techniques in the current formative period, but it
should also be understood that the course of future events is often beyond the control of statesmen.”).
3 William J. Lynn III, Deputy Secretary of Defense, Defending a New Domain: The Pentagon’s Cyberstrategy, 89
FOREIGN AFFAIRS 97, 101 (Sept./Oct. 2010) (“As a doctrinal matter, the Pentagon has formally recognized
cyberspace as a new domain of warfare. Although cyberspace is a man-made domain, it has become just as critical
to military operations as land, sea, air, and space. As such, the military must be able to defend and operate within
it.”).
4 JOINT PUBLICATION 3-12, Cyberspace Operations, GL-4 (Feb. 5, 2013) (“(U) Cyberspace. A global domain within
the information environment consisting of interdependent networks of information technology infrastructures and
resident data, including the Internet, telecommunications networks, computer systems, and embedded processors
and controllers.”).
5 JOINT PUBLICATION 3-0, Joint Operations (Aug. 11, 2011) (“cyberspace operations. The employment of
cyberspace capabilities where the primary purpose is to achieve objectives in or through cyberspace.”).
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technological developments or gaining information about an adversary’s military capabilities and
intent.
16.1.2.2 Examples of Operations That Would Not Be Regarded as Cyber
Operations. Cyber operations generally would not include activities that merely use computers
or cyberspace without a primary purpose of achieving objectives or effects in or through
cyberspace. For example, operations that use computer networks to facilitate command and
control, operations that use air traffic control systems, and operations to distribute information
broadly using computers would generally not be considered cyber operations.
Operations that target an adversary’s cyberspace capabilities, but that are not achieved in
or through cyberspace, would not be considered cyber operations. For example, the
bombardment of a network hub, or the jamming of wireless communications, would not be
considered cyber operations, even though they may achieve military objectives in cyberspace.
16.1.3 Cyber Operations - Notes on Terminology. DoD doctrine and terminology for
cyber operations continue to develop.
16.1.3.1 “Cyber” Versus “Cyberspace” as an Adjective. The terms “cyber” and
“cyberspace” when used as an adjective (e.g., cyber attack, cyber defense, cyber operation) are
generally used interchangeably.
16.1.3.2 Cyber Attacks or Computer Network Attacks. The term “attack” often
has been used in a colloquial sense in discussing cyber operations to refer to many different types
of hostile or malicious cyber activities, such as the defacement of websites, network intrusions,
the theft of private information, or the disruption of the provision of internet services.
Operations described as “cyber attacks” or “computer network attacks,” therefore, are not
necessarily “attacks” for the purposes of applying rules on conducting attacks during the conduct
of hostilities.6 Similarly, operations described as “cyber attacks” or “computer network attacks”
are not necessarily “armed attacks” for the purposes of triggering a State’s inherent right of self-
defense under jus ad bellum.7
16.2 APPLICATION OF THE LAW OF WAR TO CYBER OPERATIONS
Specific law of war rules may apply to cyber operations, even though those rules were
developed before cyber operations were possible. When no more specific law of war rule or
other applicable rule applies, law of war principles provide a general guide for conduct during
cyber operations in armed conflict.
16.2.1 Application of Specific Law of War Rules to Cyber Operations. Specific law of
war rules may be applicable to cyber operations, even though these rules were developed long
before cyber operations were possible.
6 Refer to § 16.5.1 (Cyber Operations That Constitute “Attacks” for the Purpose of Applying Rules on Conducting
Attacks).
7 Refer to § 16.3.3 (Responding to Hostile or Malicious Cyber Operations).
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The law of war affirmatively anticipates technological innovation and contemplates that
its existing rules will apply to such innovation, including cyber operations.8 Law of war rules
may apply to new technologies because the rules often are not framed in terms of specific
technological means. For example, the rules on conducting attacks do not depend on what type
of weapon is used to conduct the attack. Thus, cyber operations may be subject to a variety of
law of war rules depending on the rule and the nature of the cyber operation. For example, if the
physical consequences of a cyber attack constitute the kind of physical damage that would be
caused by dropping a bomb or firing a missile, that cyber attack would equally be subject to the
same rules that apply to attacks using bombs or missiles.9
Cyber operations may pose challenging legal questions because of the variety of effects
they can produce. For example, cyber operations could be a non-forcible means or method of
conducting hostilities (such as information gathering), and would be regulated as such under
rules applicable to non-forcible means and methods of warfare.10 Other cyber operations could
be used to create effects that amount to an attack and would be regulated under the rules on
conducting attacks.11 Moreover, another set of challenging issues may arise when considering
whether a particular cyber operation might be regarded as a seizure or destruction of enemy
property and should be assessed as such.12
16.2.2 Application of Law of War Principles as a General Guide to Cyber Operations.
When no specific rule applies, the principles of the law of war form the general guide for
conduct during war, including conduct during cyber operations.13 For example, under the
principle of humanity, suffering, injury, or destruction unnecessary to accomplish a legitimate
military purpose must be avoided in cyber operations.14
8 Harold Hongju Koh, Legal Adviser, Department of State, International Law in Cyberspace: Remarks as Prepared
for Delivery to the USCYBERCOM Inter-Agency Legal Conference (Sept. 18, 2012), reprinted in 54 HARVARD
INTERNATIONAL LAW JOURNAL ONLINE, 3 (Dec. 2012) (“Cyberspace is not a ‘law-free’ zone where anyone can
conduct hostile activities without rules or restraint. Think of it this way. This is not the first time that
technology has changed and that international law has been asked to deal with those changes. In particular, because
the tools of conflict are constantly evolving, one relevant body of law—international humanitarian law, or the law of
armed conflict—affirmatively anticipates technological innovation, and contemplates that its existing rules will
apply to such innovation.”).
9 Harold Hongju Koh, Legal Adviser, Department of State, International Law in Cyberspace: Remarks as Prepared
for Delivery to the USCYBERCOM Inter-Agency Legal Conference (Sept. 18, 2012), reprinted in 54 HARVARD
INTERNATIONAL LAW JOURNAL ONLINE, 3-4 (Dec. 2012) (“In analyzing whether a cyber operation would constitute
a use of force, most commentators focus on whether the direct physical injury and property damage resulting from
the cyber event looks like that which would be considered a use of force if produced by kinetic weapons. For
example, cyber activities that proximately result in death, injury, or significant destruction would likely be viewed as
a use of force. … Only a moment’s reflection makes you realize that this is common sense: if the physical
consequences of a cyber attack work the kind of physical damage that dropping a bomb or firing a missile would,
that cyber attack should equally be considered a use of force.”).
10 Refer to § 5.26 (Non-Forcible Means and Methods of Warfare).
11 Refer to § 5.5 (Rules on Conducting Assaults, Bombardments, and Other Attacks).
12 Refer to § 5.17 (Seizure and Destruction of Enemy Property).
13 Refer to § 2.1.2.2 (Law of War Principles as a General Guide).
14 Refer to § 2.3 (Humanity).
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Certain cyber operations may not have a clear kinetic parallel in terms of their
capabilities and the effects they create.15 Such operations may have implications that are quite
different from those presented by attacks using traditional weapons, and those different
implications may well yield different conclusions.16
16.3 CYBER OPERATIONS AND JUS AD BELLUM
Cyber operations may present issues under the law of war governing the resort to force
(i.e., jus ad bellum).17
16.3.1 Prohibition on Cyber Operations That Constitute Illegal Uses of Force Under
Article 2(4) of the Charter of the United Nations. Article 2(4) of the Charter of the United
Nations states that “[a]ll Members shall refrain in their international relations from the threat or
use of force against the territorial integrity or political independence of any state, or in any other
manner inconsistent with the Purposes of the United Nations.”18
Cyber operations may in certain circumstances constitute uses of force within the
meaning of Article 2(4) of the Charter of the United Nations and customary international law.19
For example, if cyber operations cause effects that, if caused by traditional physical means,
would be regarded as a use of force under jus ad bellum, then such cyber operations would likely
also be regarded as a use of force. Such operations may include cyber operations that: (1)
trigger a nuclear plant meltdown; (2) open a dam above a populated area, causing destruction; or
(3) disable air traffic control services, resulting in airplane crashes.20 Similarly, cyber operations
15 Harold Hongju Koh, Legal Adviser, Department of State, International Law in Cyberspace: Remarks as
Prepared for Delivery to the USCYBERCOM Inter-Agency Legal Conference (Sept. 18, 2012), reprinted in 54
HARVARD INTERNATIONAL LAW JOURNAL ONLINE, 7 (Dec. 2012) (“I have also noted some clear-cut cases where the
physical effects of a hostile cyber action would be comparable to what a kinetic action could achieve: for example,
a bomb might break a dam and flood a civilian population, but insertion of a line of malicious code from a distant
computer might just as easily achieve that same result. As you all know, however, there are other types of cyber
actions that do not have a clear kinetic parallel, which raise profound questions about exactly what we mean by
‘force.’”).
16 Department of Defense, Office of the General Counsel, An Assessment of International Legal Issues in
Information Operations (2nd ed., Nov. 1999), reprinted in 76 U.S. NAVAL WAR COLLEGE INTERNATIONAL LAW
STUDIES 459, 490 (2002) (“In the process of reasoning by analogy to the law applicable to traditional weapons, it
must always be kept in mind that computer network attacks are likely to present implications that are quite different
from the implications presented by attacks with traditional weapons. These different implications may well yield
different conclusions.”).
17 Refer to § 1.11 (Jus ad Bellum).
18 U.N. CHARTER art. 2(4).
19 Harold Hongju Koh, Legal Adviser, Department of State, International Law in Cyberspace: Remarks as
Prepared for Delivery to the USCYBERCOM Inter-Agency Legal Conference (Sept. 18, 2012), reprinted in 54
HARVARD INTERNATIONAL LAW JOURNAL ONLINE, 3 (Dec. 2012) (“Cyber activities may in certain circumstances
constitute uses of force within the meaning of Article 2(4) of the UN Charter and customary international law.”).
20 Harold Hongju Koh, Legal Adviser, Department of State, International Law in Cyberspace: Remarks as
Prepared for Delivery to the USCYBERCOM Inter-Agency Legal Conference (Sept. 18, 2012), reprinted in 54
HARVARD INTERNATIONAL LAW JOURNAL ONLINE, 4 (Dec. 2012) (“Commonly cited examples of cyber activity that
998
that cripple a military’s logistics systems, and thus its ability to conduct and sustain military
operations, might also be considered a use of force under jus ad bellum.21 Other factors, besides
the effects of the cyber operation, may also be relevant to whether the cyber operation constitutes
a use of force under jus ad bellum.22
Cyber operations that constitute uses of force within the meaning of Article 2(4) of the
Charter of the United Nations and customary international law must have a proper legal basis in
order not to violate jus ad bellum prohibitions on the resort to force.23
16.3.2 Peacetime Intelligence and Counterintelligence Activities. International law and
long-standing international norms are applicable to State behavior in cyberspace,24 and the
question of the legality of peacetime intelligence and counterintelligence activities must be
considered on a case-by-case basis. Generally, to the extent that cyber operations resemble
traditional intelligence and counter-intelligence activities, such as unauthorized intrusions into
computer networks solely to acquire information, then such cyber operations would likely be
treated similarly under international law.25 The United States conducts such activities via
cyberspace, and such operations are governed by long-standing and well-established
considerations, including the possibility that those operations could be interpreted as a hostile
act.26
16.3.3 Responding to Hostile or Malicious Cyber Operations. A State’s inherent right of
self-defense, recognized in Article 51 of the Charter of the United Nations, may be triggered by
would constitute a use of force include, for example, (1) operations that trigger a nuclear plant meltdown, (2)
operations that open a dam above a populated area causing destruction, or (3) operations that disable air traffic
control resulting in airplane crashes.”).
21 Department of Defense, Office of the General Counsel, An Assessment of International Legal Issues in
Information Operations (2nd ed., Nov. 1999), reprinted in 76 U.S. NAVAL WAR COLLEGE INTERNATIONAL LAW
STUDIES 459, 483 (2002) (“Even if the systems attacked were unclassified military logistics systems, an attack on
such systems might seriously threaten a nation’s security. For example, corrupting the data in a nation’s
computerized systems for managing its military fuel, spare parts, transportation, troop mobilization, or medical
supplies may seriously interfere with its ability to conduct military operations. In short, the consequences are likely
to be more important than the means used.”).
22 Harold Hongju Koh, Legal Adviser, Department of State, International Law in Cyberspace: Remarks as
Prepared for Delivery to the USCYBERCOM Inter-Agency Legal Conference (Sept. 18, 2012), reprinted in 54
HARVARD INTERNATIONAL LAW JOURNAL ONLINE, 4 (Dec. 2012) (“In assessing whether an event constituted a use
of force in or through cyberspace, we must evaluate factors including the context of the event, the actor perpetrating
the action (recognizing challenging issues of attribution in cyberspace), the target and location, effects and intent,
among other possible issues.”).
23 Refer to § 1.11.3 (Prohibition on Certain Uses of Force).
24 Refer to § 16.1 (Introduction).
25 Department of Defense, Office of the General Counsel, An Assessment of International Legal Issues in
Information Operations (2nd ed., Nov. 1999), reprinted in 76 U.S. NAVAL WAR COLLEGE INTERNATIONAL LAW
STUDIES 459, 518 (2002).
26 DEPARTMENT OF DEFENSE, Department of Defense Cyberspace Policy Report: A Report to Congress Pursuant to
the National Defense Authorization Act for Fiscal Year 2011, Section 934, 6-7 (Nov. 2011).
999
cyber operations that amount to an armed attack or imminent threat thereof.27 As a matter of
national policy, the United States has expressed the view that when warranted, it will respond to
hostile acts in cyberspace as it would to any other threat to the country.28
Measures taken in the exercise of the right of national self-defense in response to an
armed attack must be reported immediately to the U.N. Security Council in accordance with
Article 51 of the Charter of the United Nations.29
16.3.3.1 Use of Force Versus Armed Attack. The United States has long taken the
position that the inherent right of self-defense potentially applies against any illegal use of
force.30 Thus, any cyber operation that constitutes an illegal use of force against a State
potentially gives rise to a right to take necessary and proportionate action in self-defense.31
16.3.3.2 No Legal Requirement for a Cyber Response to a Cyber Attack. There is
no legal requirement that the response in self-defense to a cyber armed attack take the form of a
cyber action, as long as the response meets the requirements of necessity and proportionality.32
27 Harold Hongju Koh, Legal Adviser, Department of State, International Law in Cyberspace: Remarks as
Prepared for Delivery to the USCYBERCOM Inter-Agency Legal Conference (Sept. 18, 2012), reprinted in 54
HARVARD INTERNATIONAL LAW JOURNAL ONLINE, 4 (Dec. 2012) (“Question 4: May a state ever respond to a
computer network attack by exercising a right of national self-defense? Answer 4: Yes. A state’s national right
of self-defense, recognized in Article 51 of the UN Charter, may be triggered by computer network activities
that amount to an armed attack or imminent threat thereof.”); Barack Obama, International Strategy for
Cyberspace: Prosperity, Security, and Openness in a Networked World, 10 (May 2011) (“Right of Self-Defense:
Consistent with the United Nations Charter, states have an inherent right to self-defense that may be triggered by
certain aggressive acts in cyberspace.”).
28 Barack Obama, International Strategy for Cyberspace: Prosperity, Security, and Openness in a Networked
World, 14 (May 2011) (“When warranted, the United States will respond to hostile acts in cyberspace as we would
to any other threat to our country. All states possess an inherent right to self-defense, and we recognize that certain
hostile acts conducted through cyberspace could compel actions under the commitments we have with our military
treaty partners. We reserve the right to use all necessary means—diplomatic, informational, military, and
economic—as appropriate and consistent with applicable international law, in order to defend our Nation, our allies,
our partners, and our interests. In so doing, we will exhaust all options before military force whenever we can; will
carefully weigh the costs and risks of action against the costs of inaction; and will act in a way that reflects our
values and strengthens our legitimacy, seeking broad international support whenever possible.”).
29 Refer to § 1.11.5.6 (Reporting to the U.N. Security Council).
30 Refer to § 1.11.5.2 (Use of Force Versus Armed Attack).
31 Harold Hongju Koh, Legal Adviser, Department of State, International Law in Cyberspace: Remarks as
Prepared for Delivery to the USCYBERCOM Inter-Agency Legal Conference (Sept. 18, 2012), reprinted in 54
HARVARD INTERNATIONAL LAW JOURNAL ONLINE, 7 (Dec. 2012) (“To cite just one example of this, the United
States has for a long time taken the position that the inherent right of self-defense potentially applies against any
illegal use of force. In our view, there is no threshold for a use of deadly force to qualify as an “armed attack” that
may warrant a forcible response. But that is not to say that any illegal use of force triggers the right to use any and
all force in response—such responses must still be necessary and of course proportionate.”).
32 Harold Hongju Koh, Legal Adviser, Department of State, International Law in Cyberspace: Remarks as
Prepared for Delivery to the USCYBERCOM Inter-Agency Legal Conference (Sept. 18, 2012), reprinted in 54
HARVARD INTERNATIONAL LAW JOURNAL ONLINE, 4 (Dec. 2012) (“There is no legal requirement that the response
to a cyber armed attack take the form of a cyber action, as long as the response meets the requirements of necessity
and proportionality.”).
1000
16.3.3.3 Responses to Hostile or Malicious Cyber Acts That Do Not Constitute
Uses of Force. Although cyber operations that do not constitute uses of force under jus ad
bellum would not permit injured States to use force in self-defense, those injured States may be
justified in taking necessary and appropriate actions in response that do not constitute a use of
force.33 Such actions might include, for example, a diplomatic protest, an economic embargo, or
other acts of retorsion.34
16.3.3.4 Attribution and Self-Defense Against Cyber Operations. Attribution may
pose a difficult factual question in responding to hostile or malicious cyber operations because
adversaries may be able to hide or disguise their activities or identities in cyberspace more easily
than in the case of other types of operations.35
A State’s right to take necessary and proportionate action in self-defense in response to
an armed attack originating through cyberspace applies whether the attack is attributed to another
State or to a non-State actor.36
16.3.3.5 Authorities Under U.S. Law to Respond to Hostile Cyber Acts. Decisions
about whether to invoke a State’s inherent right of self-defense would be made at the national
level because they involve the State’s rights and responsibilities under international law. For
example, in the United States, such decisions would generally be made by the President.
33 Department of Defense, Office of the General Counsel, An Assessment of International Legal Issues in
Information Operations (2nd ed., Nov. 1999), reprinted in 76 U.S. NAVAL WAR COLLEGE INTERNATIONAL LAW
STUDIES 459, 482 (2002) (“There is also a general recognition of the right of a nation whose rights under
international law have been violated to take countermeasures against the offending state, in circumstances where
neither the provocation nor the response involves the use of armed force. For example, an arbitral tribunal in 1978
ruled that the United States was entitled to suspend French commercial air flights into Los Angeles after the French
had suspended U.S. commercial air flights into Paris. Discussions of the doctrine of countermeasures generally
distinguish between countermeasures that would otherwise be violations of treaty obligations or of general
principles of international law (in effect, reprisals not involving the use of armed force) and retorsions - actions that
may be unfriendly or even damaging, but which do not violate any international legal obligation. The use of
countermeasures is subject to the same requirements of necessity and proportionality as apply to self-defense.”).
34 Refer to § 18.17 (Retorsion).
35 DEPARTMENT OF DEFENSE, Department of Defense Cyberspace Policy Report: A Report to Congress Pursuant to
the National Defense Authorization Act for Fiscal Year 2011, Section 934, 4 (Nov. 2011) (“The same technical
protocols of the Internet that have facilitated the explosive growth of cyberspace also provide some measure of
anonymity. Our potential adversaries, both nations and non-state actors, clearly understand this dynamic and seek to
use the challenge of attribution to their strategic advantage. The Department recognizes that deterring malicious
actors from conducting cyber attacks is complicated by the difficulty of verifying the location from which an attack
was launched and by the need to identify the attacker among a wide variety and high number of potential actors.”).
36 United States Submission to the U.N. Group of Governmental Experts on Developments in the Field of
Information and Telecommunications in the Context of International Security 2012-2013, 2 (“As the United States
noted in its 2010 submission to the GGE, the following established principles would apply in the context of an
armed attack, whether it originated through cyberspace or not: • The right of self-defense against an imminent or
actual armed attack applies whether the attacker is a State actor or a non-State actor.”). Refer to § 1.11.5.4 (Right of
Self-Defense Against Non-State Actors).
1001
The Standing Rules of Engagement for U.S. forces have addressed the authority of the
U.S. armed forces to take action in self-defense in response to hostile acts or hostile intent,
including such acts perpetrated in or through cyberspace.37
16.4 CYBER OPERATIONS AND THE LAW OF NEUTRALITY
The law of neutrality may be important in certain cyber operations. For example, under
the law of neutrality, belligerent States are bound to respect the sovereign rights of neutral
States.38 Because of the interconnected nature of cyberspace, cyber operations targeting
networked information infrastructures in one State may create effects in another State that is not
a party to the armed conflict.39
16.4.1 Cyber Operations That Use Communications Infrastructure in Neutral States. The
law of neutrality has addressed the use of communications infrastructure in neutral States, and in
certain circumstances, these rules would apply to cyber operations.
The use of communications infrastructure in neutral States may be implicated under the
general rule that neutral territory may not serve as a base of operations for one belligerent against
another.40 In particular, belligerent States are prohibited from erecting on the territory of a
neutral State any apparatus for the purpose of communicating with belligerent forces on land or
sea, or from using any installation of this kind established by them before the armed conflict on
the territory of a neutral State for purely military purposes, and which has not been opened for
the service of public messages.41
However, merely relaying information through neutral communications infrastructure
(provided that the facilities are made available impartially) generally would not constitute a
violation of the law of neutrality that belligerent States would have an obligation to refrain from
37 See, e.g., CHAIRMAN OF THE JOINT CHIEFS OF STAFF INSTRUCTION 3121.01B, Standing Rules of
Engagement/Standing Rules for the Use of Force for U.S. Forces, ¶6b(1) (June 13, 2005), reprinted in
INTERNATIONAL AND OPERATIONAL LAW DEPARTMENT, THE JUDGE ADVOCATE GENERAL’S LEGAL CENTER &
SCHOOL, U.S. ARMY, OPERATIONAL LAW HANDBOOK 95 (2007) (“Unit commanders always retain the inherent right
and obligation to exercise unit self-defense in response to a hostile act or demonstrated hostile intent. Unless
otherwise directed by a unit commander as detailed below, military members may exercise individual self-defense in
response to a hostile act or demonstrated hostile intent.”).
38 Refer to § 15.3.1 (Neutral Rights).
39 Harold Hongju Koh, Legal Adviser, Department of State, International Law in Cyberspace: Remarks as
Prepared for Delivery to the USCYBERCOM Inter-Agency Legal Conference (Sept. 18, 2012), reprinted in 54
HARVARD INTERNATIONAL LAW JOURNAL ONLINE, 6 (Dec. 2012) (“States conducting activities in cyberspace must
take into account the sovereignty of other states, including outside the context of armed conflict. The physical
infrastructure that supports the Internet and cyber activities is generally located in sovereign territory and subject to
the jurisdiction of the territorial state. Because of the interconnected, interoperable nature of cyberspace, operations
targeting networked information infrastructures in one country may create effects in another country. Whenever a
state contemplates conducting activities in cyberspace, the sovereignty of other states needs to be considered.”).
40 Refer to § 15.5 (Prohibition on the Use of Neutral Territory as a Base of Operations).
41 Refer to § 15.5.3 (Prohibition Against Establishment or Use of Belligerent Communications Facilities in Neutral
Territory).
1002
and that a neutral State would have an obligation to prevent.42 This rule was developed because
it was viewed as impractical for neutral States to censor or screen their publicly available
communications infrastructure for belligerent traffic.43 Thus, for example, it would not be
prohibited for a belligerent State to route information through cyber infrastructure in a neutral
State that is open for the service of public messages, and that neutral State would have no
obligation to forbid such traffic. This rule would appear to be applicable even if the information
that is being routed through neutral communications infrastructure may be characterized as a
cyber weapon or otherwise could cause destructive effects in a belligerent State (but no
destructive effects within the neutral State or States).44
16.5 CYBER OPERATIONS AND JUS IN BELLO
This section addresses jus in bello rules and cyber operations.
16.5.1 Cyber Operations That Constitute “Attacks” for the Purpose of Applying Rules on
Conducting Attacks. If a cyber operation constitutes an attack, then the law of war rules on
42 Refer to § 15.5.3.1 (Use of Neutral Facilities by Belligerents Not Prohibited).
43 Colonel Borel, Report to the Conference from the Second Commission on Rights and Duties of Neutral States on
Land, in JAMES BROWN SCOTT, THE REPORTS TO THE HAGUE CONFERENCES OF 1899 AND 1907, 543 (1917) (“We
are here dealing with cables or apparatus belonging either to a neutral State or to a company or individuals, the
operation of which, for the transmission of news, has the character of a public service. There is no reason to compel
the neutral State to restrict or prohibit the use by the belligerents of these means of communication. Were it
otherwise, objections of a practical kind would be encountered, arising out of the considerable difficulties in
exercising control, not to mention the confidential character of telegraphic correspondence and the rapidity
necessary to this service. Through his Excellency Lord Reay, the British delegation requested that it be specified
that ‘the liberty of a neutral State to transmit messages, by means of its telegraph lines on land, its submarine cables
or its wireless apparatus, does not imply that it has any right to use them or permit their use in order to render
manifest assistance to one of the belligerents’. The justice of the idea thus stated was so great as to receive the
unanimous approval of the Commission.”).
44 See DEPARTMENT OF DEFENSE, Department of Defense Cyberspace Policy Report: A Report to Congress
Pursuant to the National Defense Authorization Act for Fiscal Year 2011, Section 934, 8 (Nov. 2011) (“The issue of
the legality of transporting cyber ‘weapons’ across the Internet through the infrastructure owned and/or located
in neutral third countries without obtaining the equivalent of ‘overflight rights.’ There is currently no
international consensus regarding the definition of a ‘cyber weapon.’ The often low cost of developing malicious
code and the high number and variety of actors in cyberspace make the discovery and tracking of malicious cyber
tools difficult. Most of the technology used in this context is inherently dual-use, and even software might be
minimally repurposed for malicious action.”); Department of Defense, Office of the General Counsel, An
Assessment of International Legal Issues in Information Operations (2nd ed., Nov. 1999), reprinted in 76 U.S.
NAVAL WAR COLLEGE INTERNATIONAL LAW STUDIES 459, 489 (2002) (“There need be less concern for the reaction
of nations through whose territory or communications systems a destructive message may be routed. If only the
nation’s public communications systems are involved, the transited nation will normally not be aware of the routing
such a message has taken. Even if it becomes aware of the transit of such a message and attributes it to the United
States, there would be no established principle of international law that it could point to as being violated. As
discussed above, even during an international armed conflict international law does not require a neutral nation to
restrict the use of its public communications networks by belligerents. Nations generally consent to the free use of
their communications networks on a commercial or reciprocal basis. Accordingly, use of a nation’s communications
networks as a conduit for an electronic attack would not be a violation of its sovereignty in the same way that would
be a flight through its airspace by a military aircraft.”).
1003
conducting attacks must be applied to those cyber operations.45 For example, such operations
must comport with the requirements of distinction and proportionality.46
For example, a cyber attack that would destroy enemy computer systems could not be
directed against ostensibly civilian infrastructure, such as computer systems belonging to stock
exchanges, banking systems, and universities, unless those computer systems met the test for
being a military objective under the circumstances.47 A cyber operation that would not
constitute an attack, but would nonetheless seize or destroy enemy property, would have to be
imperatively demanded by the necessities of war.48
16.5.1.1 Assessing Incidental Injury or Damage During Cyber Operations. The
proportionality rule prohibits attacks in which the expected loss of life or injury to civilians, and
damage to civilian objects incidental to the attack, would be excessive in relation to the concrete
and direct military advantage expected to be gained.49
For example, in applying the proportionality rule to cyber operations, it might be
important to assess the potential effects of a cyber attack on computers that are not military
objectives, such as private, civilian computers that hold no military significance, but that may be
networked to computers that are valid military objectives.50
In assessing incidental injury or damage during cyber operations, it may be important to
consider that remote harms and lesser forms of harm, such as mere inconveniences or temporary
losses, need not be considered in applying the proportionality rule.51 For example, a minor, brief
disruption of internet services to civilians that results incidentally from a cyber attack against a
military objective generally would not need to be considered in a proportionality analysis.52 In
45 Refer to § 5.5 (Rules on Conducting Assaults, Bombardments, and Other Attacks).
46 Refer to § 5.6 (Discrimination in Conducting Attacks); § 5.12 (Proportionality in Conducting Attacks).
47 Refer to § 5.7 (Military Objectives).
48 Refer to § 5.17.2 (Enemy Property - Military Necessity Standard).
49 Refer to § 5.12 (Proportionality in Conducting Attacks).
50 Harold Hongju Koh, Legal Adviser, Department of State, International Law in Cyberspace: Remarks as
Prepared for Delivery to the USCYBERCOM Inter-Agency Legal Conference (Sept. 18, 2012), reprinted in 54
HARVARD INTERNATIONAL LAW JOURNAL ONLINE, 8 (Dec. 2012) (“As you all know, information and
communications infrastructure is often shared between state militaries and private, civilian communities. The law of
war requires that civilian infrastructure not be used to seek to immunize military objectives from attack, including in
the cyber realm. But how, exactly, are the jus in bello rules to be implemented in cyberspace? Parties to an armed
conflict will need to assess the potential effects of a cyber attack on computers that are not military objectives, such
as private, civilian computers that hold no military significance, but may be networked to computers that are valid
military objectives. Parties will also need to consider the harm to the civilian uses of such infrastructure in
performing the necessary proportionality review. Any number of factual scenarios could arise, however, which will
require a careful, fact-intensive legal analysis in each situation.”).
51 Refer to § 5.12.2 (Types of Harm - Loss of Life, Injury, and Damage).
52 Cf. Program on Humanitarian Policy and Conflict Research at Harvard University, Commentary on the HPCR
Manual on International Law Applicable to Air and Missile Warfare, 28 (A.1.e.7) (2010) (“The definition of
‘attacks’ also covers ‘non-kinetic’ attacks (i.e. attacks that do not involve the physical transfer of energy, such as
certain CNAs [computer network attacks]; see Rule 1(m)) that result in death, injury, damage or destruction of
persons or objects. Admittedly, whether ‘non-kinetic’ operations rise to the level of an ‘attack’ in the context of the
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addition, the economic harms in the belligerent State resulting from such disruptions, such as
civilian businesses in the belligerent State being unable to conduct e-commerce, generally would
not need to be considered in a proportionality analysis.53
Even if cyber operations that constitute attacks are not expected to result in excessive
incidental loss of life or injury or damage such that the operation would be prohibited by the
proportionality rule, the party to the conflict nonetheless would be required to take feasible
precautions to limit such loss of life or injury and damage in conducting those cyber
operations.54
16.5.2 Cyber Operations That Do Not Amount to an “Attack” Under the Law of War. A
cyber operation that does not constitute an attack is not restricted by the rules that apply to
attacks.55 Factors that would suggest that a cyber operation is not an “attack” include whether
the operation causes only reversible effects or only temporary effects. Cyber operations that
generally would not constitute attacks include:
• defacing a government webpage;
• a minor, brief disruption of internet services;
• briefly disrupting, disabling, or interfering with communications; and
• disseminating propaganda.
Since such operations generally would not be considered attacks under the law of war,
they generally would not need to be directed at military objectives, and may be directed at
civilians or civilian objects. Nonetheless, such operations must not be directed against enemy
civilians or civilian objects unless the operations are militarily necessary.56 Moreover, such
operations should comport with the general principles of the law of war.57 For example, even if
a cyber operation is not an “attack” or does not cause any injury or damage that would need to be
considered under the proportionality rule, that cyber operation still should not be conducted in a
way that unnecessarily causes inconvenience to civilians or neutral persons.
16.5.3 Duty to Take Feasible Precautions and Cyber Operations. Parties to a conflict
must take feasible precautions to reduce the risk of incidental harm to the civilian population and
law of international armed conflict is a controversial issue. There was agreement among the Group of Experts that
the term ‘attack’ does not encompass CNAs that result in an inconvenience (such as temporary denial of internet
access).”).
53 Refer to § 5.12.2 (Types of Harm - Loss of Life, Injury, and Damage).
54 Refer to § 16.5.3 (Duty to Take Feasible Precautions and Cyber Operations).
55 Refer to § 5.5 (Rules on Conducting Assaults, Bombardments, and Other Attacks).
56 Refer to § 5.3.2.1 (Non-Violent Measures That Are Militarily Necessary).
57 Refer to § 16.2.2 (Application of Law of War Principles as a General Guide to Cyber Operations).
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other protected persons and objects.58 Parties to the conflict that employ cyber operations should
take precautions to minimize the harm of their cyber activities on civilian infrastructure and
users.59
The obligation to take feasible precautions may be of greater relevance in cyber
operations than other law of war rules because this obligation applies to a broader set of activities
than those to which other law of war rules apply. For example, the obligation to take feasible
precautions to reduce the risk of incidental harm would apply to a party conducting an attack
even if the attack would not be prohibited by the proportionality rule.60 In addition, the
obligation to take feasible precautions applies even if a party is not conducting an attack because
the obligation also applies to a party that is subject to attack.61
16.5.3.1 Cyber Tools as Potential Measures to Reduce the Risk of Harm to
Civilians or Civilian Objects. In some cases, cyber operations that result in non-kinetic or
reversible effects can offer options that help minimize unnecessary harm to civilians.62 In this
regard, cyber capabilities may in some circumstances be preferable, as a matter of policy, to
kinetic weapons because their effects may be reversible, and they may hold the potential to
accomplish military goals without any destructive kinetic effect at all.63
As with other precautions, the decision of which weapon to use will be subject to many
practical considerations, including effectiveness, cost, and “fragility,” i.e., the possibility that
once used an adversary may be able to devise defenses that will render a cyber tool ineffective in
the future.64 Thus, as with special kinetic weapons, such as precision-guided munitions that have
58 Refer to § 5.3.3 (Affirmative Duties to Take Feasible Precautions for the Protection of Civilians and Other
Protected Persons and Objects).
59 United States Submission to the U.N. Group of Governmental Experts on Developments in the Field of
Information and Telecommunications in the Context of International Security 2012-2013, 4 (“The law of war also
requires warring States to take all practicable precautions, taking into account military and humanitarian
considerations, to avoid and minimize incidental death, injury, and damage to civilians and civilian objects. In the
context of hostilities involving information technologies in armed conflict, parties to the conflict should take
precautions to minimize the harm of such cyber activities on civilian infrastructure and users.”).
60 Refer to § 5.11 (Feasible Precautions in Conducting Attacks to Reduce the Risk of Harm to Protected Persons and
Objects).
61 Refer to § 5.14 (Feasible Precautions to Reduce the Risk of Harm to Protected Persons and Objects by the Party
Subject to Attack).
62 Refer to § 5.11.3 (Selecting Weapons (Weaponeering)).
63 United States Submission to the U.N. Group of Governmental Experts on Developments in the Field of
Information and Telecommunications in the Context of International Security 2012-2013, 4 (“Cyber operations that
result in non-kinetic or reversible effects can be an important tool in creating options that minimize unnecessary
harm to civilians. In this regard, cyber capabilities may in some circumstances be preferable, as a matter of policy,
to kinetic weapons because their effects may be reversible, and they may hold the potential to accomplish military
goals without any destructive kinetic effect at all.”).
64 Department of Defense, Office of the General Counsel, An Assessment of International Legal Issues in
Information Operations (2nd ed., Nov. 1999), reprinted in 76 U.S. NAVAL WAR COLLEGE INTERNATIONAL LAW
STUDIES 459, 490 (2002) (“Another possible implication of a defender’s technological prowess may arise when a
nation has the capacity for graduated self-defense measures. Some may argue that a nation having such capabilities
must select a response that will do minimal damage. This is a variant of the argument that a nation possessing
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the potential to produce less incidental damage than other kinetic weapons, cyber capabilities
usually will not be the only type of weapon that is legally permitted.
16.5.4 Prohibition on Improper Use of Signs During Cyber Operations. Under the law of
war, certain signs may not be used improperly.65 These prohibitions may also be applicable
during cyber operations. For example, it would not be permissible to conduct a cyber attack or
to attempt to disable enemy internal communications by making use of communications that
initiate non-hostile relations, such as prisoner exchanges or ceasefires.66 Similarly, it would be
prohibited to fabricate messages from an enemy’s Head of State falsely informing that State’s
forces that an armistice or cease-fire had been signed.67
On the other hand, the restriction on the use of enemy flags, insignia, and uniforms only
applies to concrete visual objects; it does not restrict the use of enemy codes, passwords, and
countersigns.68 Thus, for example, it would not be prohibited to disguise network traffic as
though it came from enemy computers or to use enemy codes during cyber operations.
16.5.5 Use of Civilian Personnel to Support Cyber Operations. As with non-cyber
operations, the law of war does not prohibit States from using civilian personnel to support their
cyber operations, including support actions that may constitute taking a direct part in
hostilities.69
Under the GPW, persons who are not members of the armed forces, but who are
authorized to accompany them, are entitled to POW status.70 This category was intended to
include, inter alia, civilian personnel with special skills in operating military equipment who
precision-guided munitions must always use them whenever there is a potential for collateral damage. That position
has garnered little support among nations and has been strongly rejected by the United States. There is broad
recognition that the risk of collateral damage is only one of many military considerations that must be balanced by
military authorities planning an attack. One obvious consideration is that a military force that goes into a protracted
conflict with a policy of always using precision-guided munitions whenever there is any potential for collateral
damage will soon exhaust its supply of such munitions. Similarly, military authorities must be able to weigh all
relevant military considerations in choosing a response in self-defense against computer network attacks. These
considerations will include the probable effectiveness of the means at their disposal, the ability to assess their
effects, and the “fragility” of electronic means of attack (i.e., once they are used, an adversary may be able to devise
defenses that will render them ineffective in the future).”).
65 Refer to § 5.24 (Improper Use of Certain Signs).
66 Refer to § 12.2 (Principle of Good Faith in Non-Hostile Relations).
67 Department of Defense, Office of the General Counsel, An Assessment of International Legal Issues in
Information Operations (2nd ed., Nov. 1999), reprinted in 76 U.S. NAVAL WAR COLLEGE INTERNATIONAL LAW
STUDIES 459, 473 (2002) (“Perfidy: It may seem attractive for a combatant vessel or aircraft to avoid being attacked
by broadcasting the agreed identification signals for a medical vessel or aircraft, but such actions would be a war
crime. Similarly, it might be possible to use computer ‘morphing’ techniques to create an image of the enemy’s
chief of state informing his troops that an armistice or cease-fire agreement had been signed. If false, this would
also be a war crime.”).
68 Refer to § 5.23.1.5 (Use of Enemy Codes, Passwords, and Countersigns Not Restricted).
69 Refer to § 4.15.2.2 (Employment in Hostilities).
70 Refer to § 4.15 (Persons Authorized to Accompany the Armed Forces).
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support and participate in military operations, such as civilian members of military aircrews.71 It
would include civilian cyber specialists who have been authorized to accompany the armed
forces.
Civilians who take a direct part in hostilities forfeit protection from being made the object
of attack.72
16.6 LEGAL REVIEW OF WEAPONS THAT EMPLOY CYBER CAPABILITIES
DoD policy requires the legal review of the acquisition of weapons or weapon systems.73
This policy would include the review of weapons that employ cyber capabilities to ensure that
they are not per se prohibited by the law of war.74 Not all cyber capabilities, however, constitute
a weapon or weapons system. Military Department regulations address what cyber capabilities
require legal review.75
The law of war does not prohibit the development of novel cyber weapons. The
customary law of war prohibitions on specific types of weapons result from State practice and
opinio juris demonstrating that a type of weapon is illegal; the mere fact that a weapon is novel
or employs new technology does not mean that the weapon is illegal.76
Although which issues may warrant legal analysis would depend on the characteristics of
the weapon being assessed, a legal review of the acquisition or procurement of a weapon that
employs cyber capabilities likely would assess whether the weapon is inherently
indiscriminate.77 For example, a destructive computer virus that was programmed to spread and
destroy uncontrollably within civilian internet systems would be prohibited as an inherently
71 Refer to § 4.15 (Persons Authorized to Accompany the Armed Forces).
72 Refer to § 5.9 (Civilians Taking a Direct Part in Hostilities).
73 Refer to § 6.2 (DoD Policy of Reviewing the Legality of Weapons).
74 Harold Hongju Koh, Legal Adviser, Department of State, International Law in Cyberspace: Remarks as
Prepared for Delivery to the USCYBERCOM Inter-Agency Legal Conference (Sept. 18, 2012), reprinted in 54
HARVARD INTERNATIONAL LAW JOURNAL ONLINE, 6 (Dec. 2012) (“States should undertake a legal review of
weapons, including those that employ a cyber capability. Such a review should entail an analysis, for example, of
whether a particular capability would be inherently indiscriminate, i.e., that it could not be used consistent with the
principles of distinction and proportionality. The U.S. Government undertakes at least two stages of legal review of
the use of weapons in the context of armed conflict: first, an evaluation of new weapons to determine whether their
use would be per se prohibited by the law of war; and second, specific operations employing weapons are always
reviewed to ensure that each particular operation is also compliant with the law of war.”).
75 See, e.g., DEPARTMENT OF THE ARMY REGULATION 27-53, Review of Legality of Weapons Under International
Law (Jan. 1, 1979); SECRETARY OF THE NAVY INSTRUCTION 5000.2E, Department of the Navy Implementation and
Operation of the Defense Acquisition System and the Joint Capabilities Integration and Development System (Sept.
1, 2011); DEPARTMENT OF THE AIR FORCE INSTRUCTION 51-402, Legal Reviews of Weapons and Cyber Capabilities
(Jul. 27, 2011).
76 Refer to § 6.2.1 (Review of New Types of Weapons).
77 Refer to § 6.7 (Inherently Indiscriminate Weapons).
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indiscriminate weapon.78
78 United States Submission to the U.N. Group of Governmental Experts on Developments in the Field of
Information and Telecommunications in the Context of International Security 2012-2013, 3 (“Weapons that cannot
be directed at a specific military objective or whose effects cannot be controlled would be inherently indiscriminate,
and per se unlawful under the law of armed conflict. In the traditional kinetic context, such inherently
indiscriminate and unlawful weapons include, for example, biological weapons. Certain cyber tools could, in light
of the interconnected nature of the network, be inherently indiscriminate in the sense that their effects cannot be
predicted or controlled; a destructive virus that could spread uncontrollably within civilian internet systems might
fall into this category. Attacks using such tools would be prohibited by the law of war.”).
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XVII - Non-International Armed Conflict (NIAC)
Chapter Contents
17.1 Introduction
17.2 Application of International Law to NIACs
17.3 Special Agreements Between Parties to the Conflict
17.4 A State’s Use of Its Domestic Law and NIAC
17.5 Principle of Distinction in NIAC
17.6 Respect and Humane Treatment of Persons Taking No Active Part in
Hostilities in NIAC
17.7 Rules on Conducting Attacks in NIAC
17.8 Impartial Humanitarian Organizations and Humanitarian Activities During
NIAC
17.9 Protection of the Civilian Population in NIAC
17.10 Protection of Children in NIAC
17.11 Protection of Cultural Property in NIAC
17.12 Use of Captured or Surrendered Enemy Personnel in NIAC
17.13 Weapons in NIAC
17.14 Protection of the Wounded, Sick, Shipwrecked, and Dead in NIAC
17.15 Protection of Medical and Religious Personnel and Medical Transports in
NIAC
17.16 Display of the Distinctive Emblem in NIAC
17.17 Detention in NIAC
17.18 Non-Intervention and Neutral Duties in NIAC
17.1 INTRODUCTION
This Chapter addresses the law of war rules applicable to armed conflict not of an
international character, or non-international armed conflict (NIAC). Non-international armed
conflicts are those armed conflicts that are not between States.1 In particular, this Chapter
addresses the rules applicable to State armed forces conducting military operations against non-
State armed groups.
The application of the law of war to non-international armed conflict may be complex.2
In U.S. practice, in certain cases, the rules applicable in international armed conflict have been
applied as a matter of policy to military operations in non-international armed conflict.
17.1.1 Non-International Armed Conflict - Notes on Terminology. Non-international
armed conflict is commonly referred to by the acronym “NIAC.” Although there has been a
range of views on what constitutes a non-international armed conflict, the intensity of the
conflict and the organization of the parties are criteria that have been assessed to distinguish
1 Refer to § 3.3.1 (International Armed Conflict and Non-International Armed Conflict).
2 Refer to § 17.2 (Application of International Law to NIACs).
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between non-international armed conflict and internal disturbances and tensions, such as riots,
isolated and sporadic acts of violence, and other acts of a similar nature.3
A variety of terms have been used to describe factual situations that often may be
characterized as non-international armed conflict.
17.1.1.1 NIAC and Civil War. Civil war is a classic example of a non-
international armed conflict. For example, a non-international armed conflict could involve the
open rebellion of segments of a nation’s armed forces (sometimes called dissident armed forces)
against the incumbent regime, each claiming to be the legitimate government.4
In some cases of civil war, the insurgent party has been recognized as a belligerent, and,
at least in some respects, the law of international armed conflict would be applied by the States
choosing to recognize the insurgent party as a belligerent.5
17.1.1.2 NIAC and Internal Armed Conflict. In some cases, the term internal
armed conflict is used as a synonym for non-international armed conflict. Such usage may
reflect a traditional definition of non-international armed conflict as only those armed conflicts
occurring within the borders of a single State.6 Non-international armed conflicts, however, are
classified as such simply based on the status of the parties to the conflict, and sometimes occur in
more than one State.7 The mere fact that an armed conflict occurs in more than one State and
thus may be characterized as international “in scope” does not render it “international in
character.”8
17.1.1.3 Transnational or Internationalized NIACs. Sometimes the terms of
“transnational” or “internationalized” are used to describe certain non-international armed
conflicts.
“Transnational” has been used to indicate that the non-international armed conflict takes
place in more than one State.
3 Refer to § 3.4.2.2 (Distinguishing Armed Conflict From Internal Disturbances and Tensions).
4 See, e.g., LIEBER CODE art. 150 (“Civil war is war between two or more portions of a country or state, each
contending for the mastery of the whole, and each claiming to be the legitimate government. The term is also
sometimes applied to war of rebellion, when the rebellious provinces or portions of the state are contiguous to those
containing the seat of government.”).
5 Refer to § 3.3.3 (State Recognition of Armed Groups as Belligerents).
6 See, e.g., GC COMMENTARY 36 (“Speaking generally, it must be recognized that the conflicts referred to in Article
3 [of the GC] are armed conflicts, with armed forces on either side engaged in hostilities—conflicts, in short, which
are in many respects similar to an international war, but take place within the confines of a single country.”).
7 Refer to § 3.3.1 (International Armed Conflict and Non-International Armed Conflict).
8 Hamdan v. Rumsfeld, 548 U.S. 557, 630 (2006) (“The Court of Appeals thought, and the Government asserts, that
Common Article 3 [of the 1949 Geneva Conventions] does not apply to Hamdan because the conflict with al Qaeda,
being ‘‘international in scope,’’ does not qualify as a ‘‘conflict not of an international character.’’ 415 F. 3d, at 41.
That reasoning is erroneous. The term ‘conflict not of an international character’ is used here in contradistinction to
a conflict between nations.”).
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“Internationalized” has been used to indicate that multiple States may be involved in a
non-international armed conflict.
17.1.1.4 NIAC and Guerilla or Unconventional Warfare. Guerrilla warfare may
be understood to be military and paramilitary operations conducted in enemy-held or hostile
territory by irregular, predominantly indigenous forces.9 Guerrilla operations or unconventional
warfare are common during non-international armed conflict. Such operations, however, are a
method of warfare that has been employed in international armed conflicts and occupation as
well.
17.1.1.5 NIAC and Rebellion or Insurrection. Rebellion, insurrection, or
insurgency may also be types of non-international armed conflict.10 Counter-insurgency
operations generally occur in the context of non-international armed conflict, but could occur in
the context of an international armed conflict and occupation as well.
17.1.1.6 NIAC and Terrorism. Issues surrounding terrorism and the activities of
terrorist groups can arise in the contexts of non-international armed conflict, international armed
conflict, and, of course, can arise outside the context of armed conflict altogether. Acts of
terrorism are prohibited during international armed conflict and during non-international armed
conflict.11
17.1.1.7 NIAC and Small Wars or Low-Intensity Conflict. Non-international
armed conflict has sometimes been discussed using the term “low-intensity” conflict.12 The term
9 JOINT PUBLICATION 3-05.1, Joint Special Operations Task Force Operations, GL-11 (Apr. 26, 2007) (“guerrilla
warfare. Military and paramilitary operations conducted in enemy-held or hostile territory by irregular,
predominantly indigenous forces. Also called GW. (JP 3-05.1)”). See also FRANCIS LIEBER, GUERRILLA PARTIES
CONSIDERED WITH REFERENCE TO THE LAWS AND USAGES OF WAR 7-8 (1862) (“[B]ut it may be stated here that
whatever may be our final definition, it is universally understood in this country at the present time that a guerrilla
party means an irregular band of armed men, carrying on an irregular war, not being able, according to their
character as a guerrilla party, to carry on what the law terms a regular war. The irregularity of the guerrilla party
consists in its origin, for it is either self-constituted or constituted by the call of a single individual, not according to
the general law of levy, conscription, or volunteering; it consists in its disconnection with the army, as to its pay,
provision, and movements, and it is irregular as to the permanency of the band, which may be dismissed and called
again together at any time.”).
10 See, e.g., LIEBER CODE art. 151 (“The term rebellion is applied to an insurrection of large extent, and is usually a
war between the legitimate government of a country and portions of provinces of the same who seek to throw off
their allegiance to it and set up a government of their own.”).
11 Refer to § 10.5.3.2 (Collective Penalties and Measures of Intimidation or Terrorism); § 17.6.5 (Prohibition on
Acts of Terrorism).
12 John M. Collins, U.S. Low Intensity Conflicts, 1899-1990, 4 (Congressional Research Service, Sept. 10, 1990)
(“This survey locates LIC [Low-Intensity Conflict] on the conflict spectrum just above normal peacetime
competition and just below any kind of armed combat that depletes U.S. forces slightly, if at all (Figures 1 and 2
graphically contrast LIC with mid- and high-intensity conflicts). Limitations on violence, rather than force levels
and arsenals, determine the indistinct upper boundary of LIC. Large military formations conceivably could conduct
low-intensity operations for limited objectives using the most lethal weapons (perhaps for signalling), provided few
U.S. casualties and little U.S. damage ensued. The lower boundary, where nonviolent LICs abut normal peacetime
competition, is equally inexact. Political, economic, technological, and psychological warfare, waged for deterrent,
offensive, or defensive purposes, occupy prominent places. So do nonviolent military operations, typified by shows
of force and peacekeeping. Insurgencies, counterinsurgencies, coups d’etat, transnational terrorism,
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