The United States and Turkey have agreed "in principle" to give air support to some forces from Syria's mainstream opposition, Turkey's foreign minister said, in what if confirmed could mark an expansion of US involvement in the conflict.
US officials acknowledged ongoing discussions with Turkey about a range of options to step up the fight against Islamic State, but said no decisions had been made.
"We're in ongoing discussions with the Turks across all lines of counter-ISIL efforts. Our understanding is no decisions have been made," said one US defense official who was not authorized to speak publicly.
Washington has so far refrained from committing to enforcing a "safe zone" for Syrian rebels, as it could be seen as a declaration of war on the Syrian state.
The air support would protect Syrian rebel forces who have been trained by a US-led program on Turkish territory, said minister Mevlut Cavusoglu. The long-delayed scheme is meant to send 15,000 troops back to Syria to fight Islamic State militants.