This is a breaking story. Please check back for updates as more information becomes available. 

Rocket fire struck an air base south of Mosul, Iraq where U.S. troops are housed.

Iraqi officials spoke anonymously to the Associated Press and said it was not immediately clear if there were casualties from the rockets, which originated from Mosul and appeared to target the base 38 miles south.

An Iraqi military statement said a total of 17 rockets had struck the base, according to Reuters.

U.S. troops hosted at the base are leading an anti-terrorism coalition with Iraqi forces to counter ISIS, which still remains active in the country, primarily in sleeper cells that launch attacks on Iraqi forces.

It is not yet clear who is behind the attack, as no militant groups have yet claimed responsibility.

Some Iran-backed Iraqi militant groups have recently threatened to attack U.S. forces in Iraq as tensions rise with Iran, who is defying its 2015 nuclear accord commitments and threatening free passage of oil shipping in the Strait of Hormuz due to crippling sanctions.

Rockets have repeatedly struck nearby the U.S. Embassy in Baghdad recently, despite the heavy fortifications in the Green Zone.