Related Rule
United States of America
Practice Relating to Rule 61. Improper Use of Other Internationally Recognized Emblems
The US Air Force Pamphlet (1976) provides:
It is forbidden to make use of … the protective signs for safety zones other than as provided for in international agreements establishing these [signs] … It is also prohibited to make improper use of … the protective emblem of cultural property. 
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(c) and 8-6(b).
The US Naval Handbook (1995) states: “Protective signs and symbols may be used only to identify personnel, objects, and activities entitled to protected status which they designate. Any other use is forbidden by international law.” 
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), § 11.9.6.
The Handbook lists the protective emblem for cultural property among emblems not to be misused. 
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), §§ 11.9.4 and 12.2.
The US Naval Handbook (2007) states: “Protective signs and symbols may be used only to identify personnel, objects, and activities entitled to the protected status that they designate. Any other use is forbidden by international law.” 
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, § 8.5.1.6.
The Handbook further states that “misuse [and] abuse … [of] similar protective emblems” are examples of acts that could be considered war crimes. 
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, § 6.2.6.
In 1987, the Deputy Legal Adviser of the US Department of State affirmed: “We support the principle … that internationally recognized protective emblems … not be improperly used”. 
United States, Remarks of Michael J. Matheson, Deputy Legal Adviser, US Department of State, The Sixth Annual American Red Cross-Washington College of Law Conference on International Humanitarian Law: A Workshop on Customary International Law and the 1977 Protocols Additional to the 1949 Geneva Conventions, American University Journal of International Law and Policy, Vol. 2, 1987, p. 425.