U.S. military officials say a man believed to be an American citizen who was fighting with Islamic State militants has surrendered in Syria and is now in U.S. custody.

Maj. Adrian Rankine-Galloway, a Pentagon spokesman, says the man surrendered to Syrian Democratic forces around Tuesday and has been turned over to U.S. military forces. Galloway says the man is being legally detained as a known enemy combatant.

It's not clear if the detainee and the U.S. forces holding him are still in Syria, but the plan is to take the man into Iraq, where he would be then turned over to the U.S. State Department or Justice Department.

U.S. officials are working out what they will do with the man, if he is confirmed as an American.