The U.S. military says an American soldier has been killed in the shelling of a U.S.-Iraqi base in the northern city of Mosul.

Iraqi police say the joint base was hit by mortar rounds Tuesday.

Nobody has claimed responsibility for the attack. But it underscores the resilience of Al Qaeda in Iraq and other groups after repeated attempts to break their hold in Mosul.

The U.S. military says rounds hit the base and that one American soldier has died of wounds.