Turkey's President Recep Tayyip Erdogan has suggested he and the US are ready to drive so-called Islamic State (IS) from its Syrian stronghold of Raqqa.
Mr Erdogan said US counterpart Barack Obama floated the idea of joint action against the militants when they met at the G20 summit in China.
He said Turkey would have "no problem" with such action.
Last month Turkey launched an operation inside Syria, targeting both IS and Kurdish rebels.
Turkish-backed militia drove IS from the border town of Jarablus, but Turkey has also been concerned with checking the advance of Kurdish forces whom it regards as terrorists.
The offensive continues, and Deputy Prime Minister Nurettin Canikli said Turkish forces might push deeper into Syria after securing a stretch of land along the border.
Mr Canikli also said 110 Islamic State and Kurdish militia fighters had been killed since the operation began.
Russia, who is allied to Syrian President Bashar al-Assad, said it was "deeply concerned" by the Turkish advance.
'What is necessary will be done'
Mr Erdogan's comments on Raqqa were published in Turkish media. There has been no confirmation from the US.
"Obama wants to do some things jointly concerning Raqqa," Mr Erdogan said. "We said this would not be a problem from our perspective.''
"I said: 'Our soldiers should come together and discuss, then what is necessary will be done,'" Mr Erdogan added.
Mr Erdogan gave few other details but said more discussions would follow.
Raqqa's fall was a key point in the rise of IS as it seized swathes of territory in Iraq and Syria, and is now considered the jihadists' de facto capital.
Between 250,000-500,000 people are still thought to live there, with brutal stories emerging of the treatment of civilians.