Turkey's military intervention in Syria is a "blatant aggression in Syrian internal affairs", and results from an agreement between it, Iran and Syria's government, Redur Xelil, the spokesman for the Syrian Kurdish YPG militia said on Wednesday.
The United States has made it clear to Syrian Kurdish forces that they must return to east of the Euphrates river after seizing control of the Syrian town of Manbij to retain US support, Vice President Joe Biden said on Wednesday.
The Syrian government said on Wednesday that German Special Forces were present, alongside French and American military personnel, in northern Syria, an accusation denied by Germany.
More than 130 Islamic State group fighters have been killed in a US-backed offensive on the key jihadist-held city of Manbij in northern Syria, a monitoring group said Thursday.
Islamic State fighters have been fleeing the Syrian city of Manbij with their families as US-backed groups advance to within 6 km (4 miles) in an attack that has killed more than 150 jihadists, a spokesman for the US-backed forces said.