Related Rule
United States of America
Practice Relating to Rule 65. Perfidy
Section F. Simulation of protected status by using the distinctive emblems of the Geneva Conventions
The US Field Manual (1956) gives the following examples of “improper use of the emblem”:
using a hospital or other building accorded such protection as an observation post or military office or depot; firing from a building or tent displaying the emblem of the Red Cross; using a hospital train or airplane to facilitate the escape of combatants; displaying the emblem on vehicles containing ammunition or other non-medical stores; and in general cloaking acts of hostility. 
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, § 55.
The US Air Force Pamphlet (1976) provides:
Medical aircraft cannot retain status as protected medical aircraft during any flight in which they engage in any activity other than the transportation of patients and medical personnel or medical equipment and supplies. Use of the red cross during such a mission would be perfidious and unlawful. 
United States, Air Force Pamphlet 110-31, International Law – The Conduct of Armed Conflict and Air Operations, US Department of the Air Force, 1976, § 2-6(e).
The Pamphlet also states that “the feigning by combatants of civilian, non-combatant status” is a perfidious act. 
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(a).
The Pamphlet specifies that medical and religious personnel of the armed forces are non-combatants. 
United States, Air Force Pamphlet 110-31, International Law – The Conduct of Armed Conflict and Air Operations, US Department of the Air Force, 1976, § 3-4(c).
The US Soldier’s Manual (1984) states: “It is a serious breach of the laws of war when soldiers use these signs [red cross, red crescent and red shield of David] to protect or hide military activities.” 
United States, Your Conduct in Combat under the Law of War, Publication No. FM 27-2, Headquarters Department of the Army, Washington, November 1984, p. 7.
The US Instructor’s Guide (1985) states:
The law of war prohibits treacherous acts. For example, there were occasions in World War II when the Nazis improperly identified buildings as hospitals and certain areas as protected areas. They really used the buildings or areas for direct military purposes such as observation posts, troop billets, defensive positions, or ammunition storage … Such tactics are prohibited because they destroy the basis for the restoration of peace short of the complete destruction of one side or the other. 
United States, Instructor’s Guide – The Law of War, Headquarters Department of the Army, Washington, April 1985, p. 8.
The manual also states:
In addition to the grave breaches of the Geneva Conventions, the following acts are further examples of war crimes: … misusing the Red Cross emblem such as using a medical evacuation helicopter to transport combat troops. 
United States, Instructor’s Guide – The Law of War, Headquarters Department of the Army, Washington, April 1985, p. 13.
The US Naval Handbook (1995) states:
Misuse of protective signs, signals, and symbols … in order to injure, kill, or capture the enemy constitutes an act of perfidy. Such acts are prohibited because they undermine the effectiveness of protective signs, signals, and symbols and thereby jeopardize the safety of noncombatants and the immunity of protected structures and activities. For example, using an ambulance or medical aircraft marked with the red cross or red crescent to carry armed combatants, weapons, or ammunition with which to attack or elude enemy forces is prohibited. 
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), § 12.2.
The US Naval Handbook (2007) states:
Improperly using protective signs, signals, and symbols … to injure, kill, or capture the enemy is an act of perfidy. Such acts are prohibited because they undermine the effectiveness of protective signs, signals, and symbols and thereby jeopardize the safety of noncombatants and the immunity of protected structures and activities. For example, using an ambulance or medical aircraft marked with the red cross or red crescent to carry armed combatants, weapons, or ammunition with which to attack or elude enemy forces is prohibited. 
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, § 12.2.
In the Hagendorf case before the US Intermediate Military Government Court at Dachau in 1946, the accused, a German soldier, was charged with having “wrongfully used the Red Cross emblem in a combat zone by firing a weapon at American soldiers from an enemy ambulance displaying such emblem”. The accused was found guilty. 
United States, Intermediate Military Government Court at Dachau, Hagendorf case, Judgment, 9 August 1946.
In 1992, in its final report to Congress on the conduct of the Gulf War, the US Department of Defense stated: “Perfidious acts include … the feigning of protected status through improper use of the Red Cross or Red Crescent distinctive emblem.” 
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, p. 632.