A decision by the United States to continue to fund the Syrian Kurdish YPG militia will affect Turkey's decisions, President Recep Tayyip Erdogan said on Tuesday, ahead of a visit this week by Secretary of State Rex Tillerson.
US officials have said that Mr Tillerson expects to have difficult conversations when he visits Turkey on Thursday and Friday, given that the Nato allies have diverging interests in Syria.
Turkey has been enraged by US support for the Syrian Kurdish YPG militia, which Ankara considers a terrorist organisation and an extension of the outlawed Kurdistan Workers Party (PKK). Washington has backed the YPG in the fight against ISIL in Syria.
"Our ally's decision to give financial support to the YPG … will surely affect the decisions we will take," Mr Erdogan said in a speech to members of his ruling AK Party in parliament.
His comments followed the release of the US Department of Defence's 2019 budget, which includes funds to train and equip local forces in the fight against ISIL in Syria.
Turkey last month launched an incursion into Syria, which it calls Operation Olive Branch, to sweep the YPG from its southern border. It has also threatened to press on to the Syrian town of Manbij, under the control of a YPG-led force, and has warned American troops stationed there not to get in the way.
Washington said it has no plans to withdraw its soldiers from Manbij and two US commanders visited the town last week to reinforce that message.
"It is very clear that those who say 'we will respond aggressively if you hit us' have never experienced an Ottoman slap," Mr Erdogan said in parliament.
That was an apparent reference to comments made by US Lt Gen Paul Funk during a visit to Manbij.