Too Many Wars. Too Many Enemies

If Turkey is not bluffing, U.S. troops in Manbij, Syria, could be under fire by week’s end, and NATO engulfed in the worst crisis in its history.

Turkish President Erdogan said Friday his troops will cleanse Manbij of Kurdish fighters, alongside whom U.S. troops are embedded.

Erdogan’s foreign minister demanded concrete steps by the U.S. to end its support of the Kurds, who control the Syrian border with Turkey east of the Euphrates, all the way to Iraq.

If the Turks attack Manbij, the U.S. w...