Related Rule
United States of America
Practice Relating to Rule 147. Reprisals against Protected Objects
Section C. Cultural property
The US Air Force Pamphlet (1976) provides: “Reprisals against protected cultural property are not taken because of their questionable legality.” 
United States, Air Force Pamphlet 110-31, International Law – The Conduct of Armed Conflict and Air Operations, US Department of the Air Force, 1976, § 10-7(b)(2).
The US Air Force Commander’s Handbook (1980), under the heading “Persons and Things Not Subject to Reprisals”, lists a number of persons and objects protected under the 1949 Geneva Conventions against whom reprisals are prohibited. It adds, however:
A Protocol to the 1949 Geneva Conventions would expand this list to include … cultural property … The United States signed this Protocol in 1977, but has not yet ratified it. Consult the Staff Judge Advocate for further guidance. 
United States, Air Force Pamphlet 110-34, Commander’s Handbook on the Law of Armed Conflict, Judge Advocate General, US Department of the Air Force, 25 July 1980, § 8-4(c).
The US Operational Law Handbook (1993) provides:
The following measures are expressly prohibited by the law of war and are not excusable on the basis of military necessity:
m. Reprisals against … religious or cultural edifices. 
United States, Operational Law Handbook, JA 422, Center for Law and Military Operations and International Law Division, The Judge Advocate General’s School, United States Army, Charlottesville, Virginia 22903-1781, 1993, p. Q-182.
In 1987, in submitting the 1977 Additional Protocol II to the US Senate for advice and consent to ratification, the US President announced his decision not to ratify the 1977 Additional Protocol I, stating, inter alia, that the Additional Protocol I “fails to improve substantially the compliance and verification mechanisms of the 1949 Geneva Conventions and eliminates an important sanction against violations of those Conventions”. 
United States, Message from the US President transmitting the 1977 Additional Protocol II to the US Senate for advice and consent to ratification, Treaty Doc. 100-2, 29 January 1987.
In 1987, the Deputy Legal Adviser of the US Department of State stated that the United States did not support “the prohibition on reprisals in article 51 [of the 1977 Additional Protocol I] and subsequent articles” and did not consider it part of customary law. 
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 Journal of International Law and Policy, Vol. 2, 1987, p. 426.
In its written statement submitted to the ICJ in the Nuclear Weapons case in 1995, the United States stated:
Various provisions of Additional Protocol I contain prohibitions on reprisals against specific types of persons or objects, including … cultural objects and places of worship (Article 53(c)) … These are among the new rules established by the Protocol that … do not apply to nuclear weapons. 
United States, Written statement submitted to the ICJ, Nuclear Weapons case, 20 June 1995, p. 31.