Three U.S. troops were killed in a drone attack in Jordan near the border of Syria, where Iran-backed militias have conducted more than 150 attacks on bases hosting U.S. troops in recent months.

A one-way attack drone crashed into the Jordanian base Saturday night, killing three U.S. service members and injuring more than 30. One of the Iran-backed militant groups operating in Syria and Iraq carried out the attack, but the facts of the incident were still being assessed, the White House also said.