Firefighting efforts have been hampered by the presence of mines and unexploded ordnance left over from the civil war, as the country grapples with the worst drought in decades.

Thomas J. Barrack Jr., the U.S. ambassador to Turkey, says Washington is facilitating the discussions and prioritizing economic development over nation-building in the Middle East.

During Syria’s civil war, the Islamic State captured a large chunk of eastern Syrian and ruled over it for years. A U.S.-led ...