A U.S service member was killed in Iraq Tuesday as the military bolstered its role helping Christian and Kurdish militias battle ISIS close to the terror group's stronghold in Mosul.br "It is a combat death, of course.br And a very sad loss," said U.S. Secretary of Defense Ash Carter.br The troop killed was an American advisor to the Kurdish Peshmerga force and was working with a Peshmerga unit 2-3 miles behind the front line during a battle with ISIS when militants advanced into Kurdish territory to kill the American with gun fire.