Baghdad — Four members of Iraq's military were wounded Sunday in a rocket attack targeting an air base north of Baghdad that often hosts American troops, Iraqi security officials said. The attack by at least six rockets came just days after Iran fired ballistic missiles at two bases in Iraq that house U.S. forces, causing no casualties.

Recent heightened tensions between the U.S. and Iran were sparked last month when a rocket attack killed an American contractor at a base in Iraq. The U.S. has blamed that attack and others on Iran-backed militias.

Sunday's attack wounded an Iraqi Air Force officer and three enlisted men, Iraqi security officials said. They spoke on condition of anonymity in line with regulations.

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No group claimed responsibility for the attack.

The rockets struck Balad Air Base, which hosts American trainers, advisers and a company that provides maintenance services for F-16 aircraft. Some rockets fell on a restaurant inside the airbase, the officials said.

The base is located some 50 miles miles north of Baghdad.

An aerial photo of Joint Base Balad, Iraq. Sergeant Quentin Johnson via DVIDS

A statement from the Iraqi Army's official media office confirmed the attack, but said eight rockets hit the base, and that two officers had been wounded. The difference in accounts could not immediately be reconciled.

There are no Americans currently at Balad Air Base, according to a coalition spokesperson. A defense official said American experts, trainers and advisers had been at the base. The official spoke on condition of anonymity because he was not authorized to speak to media.

The U.S. and Iran recently stepped back from escalating tensions following the killing of General Qassem Soleimani, Iran's top general, in a U.S. airstrike in Baghdad. A senior Iraqi leader of an Iran-backed militia was also killed.

Iran's retaliatory attack for Soleimani's death hit two Iraqi bases, Ain al-Asad and Erbil, where American troops are based.