Armed Turkish military vehicles crossed into northeast Syria on Sunday to begin planned joint U.S.-Turkey patrols to establish a "safe zone" along the border.
A Reuters witness said vehicles with Turkish flags joined those in Syria with U.S. flags some 15 kilometers (nine miles) east of the Turkish border town of Akcakale, near Syria's Tel Abyad. The region east of the Euphrates river is mainly controlled by Kurdish YPG forces.