Related Rule
United States of America
Practice Relating to Rule 57. Ruses of War
The US Field Manual (1956) states:
Ruses of war and the employment of measures necessary for obtaining information about the enemy and the country are considered permissible.
Absolute good faith with the enemy must be observed as a rule of conduct; but this does not prevent measures such as using spies and secret agents, encouraging defection or insurrection among the enemy civilian population, corrupting enemy civilians or soldiers by bribes, or inducing the enemy’s soldiers to desert, surrender, or rebel. In general, a belligerent may resort to those measures for mystifying or misleading the enemy against which the enemy ought to take measures to protect himself.
Ruses of war are legitimate so long as they do not involve treachery or perfidy on the part of the belligerent resorting to them. They are, however, forbidden if they contravene any generally accepted rule.
The line of demarcation between legitimate ruses and forbidden acts of perfidy is sometimes indistinct … [I]t is a perfectly proper ruse to summon a force to surrender on the ground that it is surrounded and thereby induce such surrender with a small force.
Among legitimate ruses may be counted surprises; ambushes; feigning attacks, retreats or flights; simulating quiet and inactivity; use of small forces to simulate large units; transmitting false or misleading radio or telephone messages; deception of the enemy by bogus orders purporting to have been issued by the enemy commanders; making use of the enemy’s signals and passwords; pretending to communicate with troops or reinforcements which have no existence; deceptive supply movements; deliberate planting of false information; use of spies and secret agents; moving landmarks; putting up dummy guns and vehicles or laying dummy mines; erection of dummy installations and airfields; removing unit identifications from uniforms; use of signal deceptive measures; and psychological warfare activities. 
United States, Field Manual 27-10, The Law of Land Warfare, US Department of the Army, 18 July 1956, as modified by Change No. 1, 15 July 1976, §§ 48–51.
The US Air Force Pamphlet (1976) states:
Ruses of war which have customarily been accepted as lawful, such as the use of camouflage, traps, mock operations and misinformation, are not perfidy. Ruses of war involve misinformation, deceit or other steps to mislead the enemy under circumstances where there is no obligation to speak the truth.
Article 24 of the 1907 Hague Regulations confirms the general rule that ruses of war not constituting perfidy are lawful. Among the permissible ruses are surprises, ambushes, feigning attacks, retreats, or flights; simulation of quiet and inactivity; use of small forces to simulate large units; transmission of false or misleading radio or telephone messages (not involving protection under international law such as internationally recognized signals of distress); deception by bogus orders purported to have been issued by the enemy commander; use of the enemy’s signals and passwords; feigned communication with troops or reinforcements which have no existence; and resort to deceptive supply movements. Also included are the deliberate planting of false information, moving of landmarks, putting up dummy guns and vehicles, laying of dummy mines, erection of dummy installations and airfields, removal of unit identifications from uniforms, and use of signal deceptive measures.
The following examples provide guidelines for lawful ruses:
(1) The use of aircraft decoys. Slower or older aircraft may be used as decoys to lure hostile aircraft into combat with faster and newer aircraft held in reserve. The use of aircraft decoys to attract ground fire in order to identify ground targets for attack by more sophisticated aircraft is also permissible.
(2) Staging air combats. Another lawful ruse is the staging of air combat between two properly marked friendly aircraft with the object of inducing an enemy aircraft into entering the combat in aid of a supposed comrade.
(3) Imitation of enemy signals. No objection can be made to the use by friendly forces of the signals or codes of an adversary. The signals or codes used by enemy aircraft or by enemy ground installations in contact with their aircraft may properly be employed by friendly forces to deceive or mislead an adversary. However, misuse of distress signals or distinctive signals internationally recognized as reserved for the exclusive use of medical aircraft would be perfidious.
(4) Use of flares and fires. The lighting of large fires away from the true target area for the purpose of misleading enemy aircraft into believing that the large fires represent damage from prior attacks and thus leading them to the wrong target is a lawful ruse. The target marking flares of the enemy may also be used to mark false targets. However, it is an unlawful ruse to fire false target flare indicators over residential areas of a city or town which are not otherwise valid military objectives.
(5) Camouflage use. The use of camouflage is a lawful ruse for misleading and deceiving enemy combatants. The camouflage of a flying aircraft must not conceal national markings of the aircraft, and the camouflage must not take the form of the national markings of the enemy or that of objects protected under international law.
(6) Operational ruses. The ruse of the “switched raid” is a proper method of aerial warfare in which aircraft set a course, ostensibly for a particular target, and then, at a given moment, alter course in order to strike another military objective instead. This method was utilized successfully in World War II to deceive enemy fighter intercepter aircraft. 
United States, Air Force Pamphlet 110-31, International Law – The Conduct of Armed Conflict and Air Operations, US Department of the Air Force, 1976, §§ 8–3(b), 8-4(a) and (b).
The US Naval Handbook (1995) states:
The law of armed conflicts permits deceiving the enemy through stratagems and ruses of war intended to mislead him, to deter him from taking action, or to induce him to act recklessly, provided the ruses do not violate rules of international law applicable to armed conflict.
Stratagems and ruses of war permitted in armed conflict include such deceptions as camouflage, deceptive lighting, dummy ships and other armament, decoys, simulated forces, feigned attacks and withdrawals, ambushes, false intelligence information, electronic deceptions, and utilization of enemy codes, passwords, and countersigns. 
United States, The Commander’s Handbook on the Law of Naval Operations, NWP 1-14M/MCWP 5-2.1/COMDTPUB P5800.7, issued by the Department of the Navy, Office of the Chief of Naval Operations and Headquarters, US Marine Corps, and Department of Transportation, US Coast Guard, October 1995 (formerly NWP 9 (Rev. A)/FMFM 1-10, October 1989), §§ 12.1 and 12.1.1.
The US Naval Handbook (2007) states:
12.1 General
The law of armed conflict permits deceiving the enemy through stratagems and ruses of war intended to mislead him, to deter him from taking action, or to induce him to act recklessly, provided the ruses do not violate rules of international law applicable to armed conflict.
12.1.1 Permitted Deceptions
Stratagems and ruses of war permitted in armed conflict include such deceptions as camouflage; deceptive lighting; dummy ships and other armament; decoys; simulated forces; feigned attacks and withdrawals; ambushes; false intelligence information; electronic deceptions; and utilization of enemy codes, passwords, and countersigns. 
United States, The Commander’s Handbook on the Law of Naval Operations, NWP 1-14M/MCWP 5-12.1/COMDTPUB P5800.7, issued by the Department of the Navy, Office of the Chief of Naval Operations and Headquarters, US Marine Corps, and Department of Homeland Security, US Coast Guard, July 2007, §§ 12.1 and 12.1.1.
The US Manual for Military Commissions (2010), Part IV, Crimes and Elements, states: “Ruses of war are legitimate so long as they do not involve treachery or perfidy on the part of the belligerent resorting to them. They are, however, forbidden if they contravene any generally accepted rule.” 
United States, Manual for Military Commissions, published in implementation of Chapter 47A of Title 10, United States Code, as amended by the Military Commissions Act of 2009, 10 U.S.C, §§ 948a, et seq., 27 April 2010, § 5(17)(c)(1), p. IV-14.
In 1992, in its final report to Congress on the conduct of the Gulf War, the US Department of Defense stated:
Under the law of war, deception includes those measures designed to mislead the enemy by manipulation, distortion, or falsification of evidence to induce him to react in a manner prejudicial to his interests. Ruses are deception of the enemy by legitimate means, and are specifically allowed by Article 24, [of the 1907 Hague Regulations], and [the 1977 Additional Protocol I]
Coalition actions that convinced Iraqi military leaders that the ground campaign to liberate Kuwait would be focused in eastern Kuwait, and would include an amphibious assault, are examples of legitimate ruses …
There were few examples of perfidious practices during the Persian Gulf War. The most publicized were those associated with the battle of Ras Al-Khafji, which began on 29 January. As that battle began, Iraqi tanks entered Ras Al-Khafji with their turrets reversed, turning their guns forward only at the moment action began between Iraqi and Coalition forces. While there was some media speculation that this was an act of perfidy, it was not; a reversed turret is not a recognized indication of surrender per se. Some tactical confusion may have occurred, since Coalition ground forces were operating under a defensive posture at that time, and were to engage Iraqi forces only upon clear indication of hostile intent, or some hostile act. 
United States, Department of Defense, Final Report to Congress on the Conduct of the Persian Gulf War, 10 April 1992, Appendix O, The Role of the Law of War, ILM, Vol. 31, 1992, pp. 631–632.