Responding to Vladimir Putin and Bashar Assad’s escalating slaughter of Syrian civilians, Turkey is surging more forces into northern Syria’s Idlib governate. President Recep Tayyip Erdogan is trying to send Putin a message: Stop your offensive.

Syrian regime forces launched attacks on Turkish positions in Idlib this week, killing a number of soldiers. Turkey has retaliated in kind. And Turkey has pushed back hard against Russian denials that Moscow was given a deconfliction notice by Ankara of its deployment locations. That deconfliction channel is designed to prevent Syrian forces from attacking Turkish forces. The Russians are lying here, and Turkey knows it. The tension between Russia and Turkey is unlikely to lead to a direct exchange of fire, but it might.