Turkey’s embattled authoritarian President Recep Tayyip Erdogan’s bluff with refugees at the gates of Europe seems to have misfired as the EU is closing ranks with Greece and is shutting down its southern border, while squarely laying the blame on Erdogan for the looming humanitarian crisis.

After suffering casualties last week in the fighting against Syria’s Russia-backed forces around Idlib, the last bastion of the anti-Assad insurgency, Erdogan said he will no longer stick to an agreement th...