The last U.S. troops were slated to leave Iraq on Wednesday under an agreement between Baghdad and Washington, a move celebrated by Iran-backed groups but which some other Iraqis found concerning, particularly in the Kurdish region.

U.S. troops invaded Iraq in 2003 to topple Saddam Hussein. They departed in 2011, but three years later, Iraqi authorities invited a smaller U.S.-led mission to fight the Islamic State group, which had rampaged across Iraq, seizing large swaths of territory.