Turkey sends more tanks to Syria, insists on Kurdish retreat

American allies that would also jeopardize the fight against the Islamic State group in the volatile area.

Turkey’s incursion Wednesday to capture the town of Jarablus was a dramatic escalation of Turkey’s role in Syria’s war and adds yet another powerhouse force on the ground in an already complicated conflict.

But Ankara’s objective went beyond fighting extremists. Turkey is also aiming to contain the expansion by Syria’s Kurds, who have used the fight against IS and the chaos of Syria’s civil war to seize nearly the entire stretch of territory along Syria’s northern border with Turkey.

Above all, Ankara seeks to avoid Kurdish forces linking up their strongholds along the border. The U.S. has backed its NATO ally, sending a stern warning to the Syrian Kurds with whom it has partnered in the fight against IS to stay east of the Euphrates River.

“The U.S. is interested in stopping this from becoming a confrontation between the YPG and Turkey. That would be a huge detriment to the anti-IS campaign,” said Chris Kozak, a Syria researcher at the Washington-based Institute of the Study of War, referring to the main U.S.- backed Kurdish faction fighting IS.

Kozak said an open confrontation between Turkey and the Kurds in Syria would undo much of the progress made working with the Kurdish forces against IS in northern Syria. If there are direct clashes, the U.S. would be forced to take sides, he said, and Washington would likely side with its NATO ally, whose air base is used to launch coalition airstrikes against the extremists in Syria and Iraq.

On Thursday, Turkish officials said Syrian Kurdish forces had started withdrawing east of the Euphrates River.