U.S. officials on Friday would not confirm the authenticity of the video. But if the slurs were uttered by supposed allies in the fight against IS, it is “unacceptable and reprehensible,” Kirby told reporters.
The U.S. Defense Department has previously acknowledged its special operations teams are accompanying Turkish and some Syrian opposition armed personnel in the area and further east, near Jarablus.
Meanwhile, Turkish-backed rebels, according to Ankara, have been involved in deadly clashes with IS in northern Syria with the support of Turkish warplanes and tanks.
It is hoped that the truce forged by the United States and Russia will clear the way for negotiations about a political transition in Syria. But rebel leaders say they expect the cease-fire to collapse and do not believe Syrian President Bashar al-Assad — or his foreign backers, Russia and Iran — want to negotiate a political settlement.
“The armed groups on the ground are still discussing what they should do about the cease-fire,” General Salim Idris, former chief of the staff of the Free Syrian Army, told VOA.