Two rockets struck a base housing American troops in eastern Syria on Wednesday without causing any human or material losses, the U.S. military said.

The morning attack on Mission Support Site Conoco came as Iran and its allies in the region marked the third anniversary of the killing of Iran’s elite Quds force chief Gen. Qassem Soleimani, in a U.S. drone strike in Baghdad.

No one claimed responsibility for the attack in east Syria, where it is not uncommon for bases housing U.S. troops to come under rocket fire or mortar attacks. Iran-backed militia are based nearby as are sleeper cells of the Islamic State group that was defeated in Syria in March 2019.

The Britain-based Syrian Observatory for Human Rights, an opposition war monitor, said the rockets were fired by Arab tribesmen in the region who are armed by Iran.

“Attacks of this kind place Coalition Forces and the civilian populace at risk and undermine the hard-earned stability and security of Syria and the region,” said Joe Buccino, spokesman for US Central Command, in a statement.

CENTCOM said members of the Kurdish-led and U.S.-backed Syrian Democratic Forces visited the rocket origin site and found a third that was not fire.

There are roughly 900 U.S. troops in Syria, including in the north and farther south and east.

(AP)