Redeploying an energy survey vessel into Greece’s exclusive economic zone, President Recep Tayyip Erdogan of Turkey has proved that he requires sanctioning.

It is obvious that Erdogan is challenging the European Union to live up to its sanction threats. Following the Oruc Reis’ previous survey in August, the Turkish leader agreed to keep the vessel in port so as to facilitate dialogue with the EU and Greece. But his motives weren’t altruistic. Recognizing that Turkey’s actions are incompatible with Greece’s sovereign rights, the EU had threatened sanctions if Erdogan’s surveys continued. Erdogan, for a time, seemed to be inclined toward compromise. But this new survey proves that Erdogan has chosen to double down on escalation.