Turkish president Recep Tayyip Erdogan has called on Nato to take a stand against the United States over its plans to form a 30,000-strong Kurdish-led border security force in Syria.
Turkey has threatened to launch a military offensive against Syrian Kurdish militias, which Ankara considers to be terrorists.
On Monday, Mr Erdogan accused fellow Nato ally the US of creating an "army of terror" in Syria along the border with Turkey, and vowed to crush the force.
Addressing his ruling party’s deputies on Tuesday, Mr Erdogan questioned Nato’s stance on the issue, saying: "Hey Nato! You are obliged to make a stance against those who harass and violate the borders of your members."
Mr Erdogan said Turkey’s military chief would discuss the issue in Brussels.