A U.S. MV-22 Osprey aircraft went down in a "hard landing" in Syria on Friday and two troops were treated for injuries, military officials said.

The incident occurred early in the morning and the cause was being investigated, according to U.S. Central Command.

The two injured troops were taken to a treatment facility for medical care and then released. No casualties or other injuries were reported.

The U.S. is backing Syria Democratic Forces there in the fight against the Islamic State.

The coalition is moving closer to taking the extremist group's de facto capital of Raqqa but has been converging with Russian and Syria regime forces, causing concerns over clashes.