Related Rule
United States of America
Practice Relating to Rule 31. Humanitarian Relief Personnel
In 1992, in a report submitted pursuant to paragraph 5 of UN Security Council Resolution 771 (1992) on grave breaches of the 1949 Geneva Convention IV committed in the former Yugoslavia, the United States included among “deliberate attacks on non-combatants” a report that “snipers fired all day at United Nations personnel as they distributed food to people in Sarajevo”. 
United States, Former Yugoslavia: Grave Breaches of the Fourth Geneva Convention, annexed to Letter dated 22 September 1992 to the UN Secretary-General, UN Doc. S/24583, 23 September 1992, p. 8.
During a press briefing on 17 December 1996, an official spokesperson for the US Department of State characterized the killing of six ICRC medical aid workers in Chechnya as “a barbarous act” and condemned it in the strongest possible terms. 
United States, Department of State Daily Press Briefing, 17 December 1996.
According to the Report on US Practice, it is the opinio juris of the United States that “unjustified attacks on international relief workers are also violations of international humanitarian law”. 
Report on US Practice, 1997, Chapter 4.2.