Here’s what may be driving a US troop withdrawal from Syria

Reports of a total and immediate withdrawal of U.S. troops from Syria come amid heightening tensions — and growing risk of military confrontation — between the U.S. and Turkey.

Turkish forces want to push their troops into Syria. The U.S.-backed Syrian Kurds want to keep the Turkish forces out. And the U.S. has struggled for months to keep both players happy.

A confrontation between the U.S and Turkey, officially NATO allies, would create a geopolitical crisis at the heart of the world’s most powerful military alliance.

Northern Syria has been popping up in the news a lot over the past year, with periodic developments in a tangled web of paramilitary group acronyms and overlapping allegiances.

Caught in the middle are an unknown number of U.S. troops — estimated to be around 2,000 — who man outposts in the region for the stated purpose of preventing a resurgence of the Islamic State.

“Turkey has legitimate security concerns,” U.S. Defense Secretary Jim Mattis said in January. “[Turkish leaders] have been very supportive of our Defeat-ISIS campaign, allowing us to use Incirlik [Air Base] to fly out of. … The area where we’ve had disagreement [is] on our tactical collaboration with the Syrian Democratic Forces … a sizable percentage of which is YPG.”

To Turkey, the SDF’s Kurdish fighters are replacing one security threat — ISIS — with another — the People’s Protection Units, or YPG.

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