Ankara and Washington have long been at odds over Syria policy, where the United States has backed the YPG.
Turkey will start an operation east of the Euphrates river in northern Syria in a "few days" President Recep Tayyip Erdoğan said on Wednesday, a move that could further complicate relations with the United States.
"We will start the operation to clear the East of the Euphrates from separatist terrorists in a few days. Our target is never U.S. soldiers," Erdoğan said in a speech.
The YPG is the armed wing of the Democratic Union Party (PYD), which is the Syrian offshoot of the Kurdistan Workers' Party (PKK). The PKK is listed as a terrorist organization by Turkey, the European Union and the United States.