“The direct US participation in military operations with Israeli forces means that as a matter of international law, the United States has been and currently is a party to the armed conflict in Gaza,” said Sarah Yager, Washington director at Human Rights Watch. “US military and intelligence personnel and contractors assisting Israeli forces who commit war crimes may at some point find themselves facing criminal prosecution for atrocities in Gaza.”

Under international humanitarian law, the ongoing hostilities between Israel and Palestinian armed groups in Gaza is a non-international armed conflict. International law does not set out specific criteria for determining when a country assisting another country in a non-international armed conflict itself becomes a party to that conflict, though direct participation in combat operations is a clear example.