Officials did not provide the exact number of troops wounded in the attack or the severity of the injuries. They spoke on condition of anonymity to describe details before they were made public. Such attacks have taken place on several occasions over the past few months, with U.S. officials for the most part blaming Iran-backed fighters.
Col. Myles Caggins, a spokesman for the U.S.-led coalition fighting Islamic State forces in Iraq and Syria, said Iraqi security forces were leading the investigation and response to the attack. Iraq has been roiled since Oct. 1 by protests that have left more than 450 people dead, the vast majority of them demonstrators killed by security forces firing tear gas and live ammunition. The mass uprisings prompted the resignation of former Prime Minister Adel Abdul-Mahdi late last month.