Turkey's President Tayyip Erdogan expressed concerns over the actions and presence of Kurdish militia fighters in a phone call about Syria with US President Donald Trump, the Turkish presidency said.
It said the two leaders agreed on the need for more efficient cooperation over Syria, without giving details.
Erdogan said on Wednesday Turkey would launch a military operation against the US-backed Syrian Kurdish YPG militia, prompting a warning from the Pentagon that any such military action would be unacceptable.