The US and Turkey, whose forces are at loggerheads in northern Syria, have agreed to try to defuse the crisis.
The Nato allies said joint teams would meet straight away to work through their diplomatic differences, including a dispute over the city of Manbij.
Turkey has threatened to attack US-allied Kurdish forces in Manbij, whom they regard as terrorists.
Pro-Turkish forces are battling the militia in nearby Afrin, across Turkey’s southern border with Syria.
The US also has soldiers in Manbij, which was taken from the Islamic State group (IS) by forces led by the Kurdish People’s Protection Units (YPG) in 2016.
Last week, a top US general said his forces would “respond aggressively” to any Turkish-backed attack on Manbij.
In response, Turkish President Recep Tayyip Erdogan threatened the US with an “Ottoman slap” – a historical reference to a supposedly deadly blow.