The US is to stop supplying arms to the Syrian Kurdish militia the YPG, Turkey has said.
Foreign Minister Mevlut Cavusoglu said President Donald Trump had made the promise in a phone call to his Turkish counterpart, Recep Tayyip Erdogan.
The White House said it was making "adjustments" to its support for partners inside Syria but did not explicitly name the YPG.
Turkey has long complained about US support for the group.
Washington has viewed the YPG as a key player in the fight against so-called Islamic State (IS), but Ankara brands the group's fighters as terrorists.
Turkey says the YPG is as an extension of the outlawed Kurdistan Workers Party (PKK), a group it has been fighting for decades in south-eastern Turkey.