Iran fired 15 ballistic missiles at Iraqi bases housing US and coalition troops on Tuesday night, a US Central Command spokesperson confirmed to Al-Monitor, in a possible escalation of tensions between the United States and Iran after a Pentagon drone strike killed a top Iranian military leader last week.

Of the 15 missiles fired, 10 struck Al-Asad Air Base in Iraq’s western Anbar province, while one struck Erbil Airport in the Kurdistan region of northern Iraq, though journalists in the area said reporting on the strike was inaccurate. Four of the missiles failed in flight, the spokesperson said.

The Islamic Revolutionary Guard Corps claimed responsibility for the strikes, the first time in recent memory that Iran has fired ballistic missiles against US targets. CNN reported that there had been Iraqi casualties in the strike on Al-Asad.

A defense official later said that the Pentagon is still conducting damage assessments and that Pentagon leadership had contacted regional and NATO allies. “All of the phone calls that were made were taken,” the official stated, batting back a report that Iraqi caretaker Prime Minister Adel Abdul Mahdi had rejected a call from Defense Secretary Mark Esper.