Related Rule
United States of America
Practice Relating to Rule 88. Non-Discrimination
Section B. Civilians
The US Field Manual (1956) restates Article 13 of the 1949 Geneva Convention IV. 
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, § 252.
The US Air Force Pamphlet (1976) refers to Article 27 of the 1949 Geneva Convention IV and states: “Any distinction in treatment based upon race, religion or political opinion is specifically forbidden.” 
United States, Air Force Pamphlet 110-31, International Law – The Conduct of Armed Conflict and Air Operations, US Department of the Air Force, 1976, § 14-4.