BAGHDAD, May 14 (Reuters) - A U.S. soldier was killed in an attack on his patrol in Salah ad-Din province north of Baghdad, the U.S. military said on Monday. It said in a statement the attack occurred on Sunday and involved an explosion but gave no other details. More than 3,390 U.S. soldiers have been killed in action in Iraq since the March 2003 U.S.-led invasion to topple Saddam Hussein.
