U.S. air defenses at a remote military outpost in Jordan failed to stop a deadly drone attack yesterday because it arrived at the same time that an American drone was returning to base, American officials said.

Three U.S. service members died in the strike, the first known American military deaths in the conflict that has spilled over from the Israel-Hamas war. The Pentagon identified the dead soldiers as Sgt. William Jerome Rivers, 46; Spec. Kennedy Ladon Sanders, 24; and Spec. Breonna Alexsondria Moffett, 23.

The returning American craft prompted confusion over whether the hostile drone — which U.S. officials said had the “footprints of Kataib Hezbollah,” an Iran-affiliated group in Iraq — was friendly, and air defenses were not immediately activated. The drone landed near the living quarters of Tower 22, an American resupply base in northeast Jordan near Syria and Iraq. Two other nearby attack drones were shot down.

President Biden, who has vowed to retaliate, could order strikes on Iran’s proxy forces, a major escalation of the attacks he has already conducted in Syria, Iraq and Yemen. But those strikes haven’t deterred the militias.

He could also go after Iranian suppliers of drones and missiles, perhaps even inside the country’s territory. But that could open another front in the war, with a far more powerful adversary. My colleague David Sanger reported on Biden’s options.