[European Commission President Juncker addresses the European Parliament during a debate in Strasbourg]European Commission President Jean-Claude Juncker delivered a personal warning to Turkish President Tayyip Erdogan on Tuesday that he would be held responsible if Ankara fails to meet EU criteria for granting Turks visa-free travel. An EU offer to liberalise its visa system was part of a deal in March under which Turkey has agreed to all but halt the flow of Syrian refugees and other migrants into the EU via Greece. "Everything the Turkish authorities are doing today leads me to believe that in the end Turkey does not want to be ready to respect European standards," he said.