Turkish president Recep Tayyip Erdogan has vowed to "drown" a 30,000-strong border Syrian Kurdish border security force being set up by the United States.
Mr Erdogan accused the US, a Nato ally, of forming a "terrorist force" at Turkey’s border.
Ankara considers the Syrian Kurdish militia to be a terror group, claiming it is affiliated with Turkey’s own outlawed Kurdish rebels fighting against the government.
The Turkish president said his government’s "duty is to drown this terrorist force before it is born".
Mr Erdogan also said Turkey’s military deployed at the border with Syria is now striking Syrian Kurdish fighters heavy artillery, and vowed to "continue to strike them".