Turkey today threatened to allow tens of thousands of refugees to leave for Europe.<br />''<br />'' At the Turkish border, Greek police clashed with several thousand migrants who were already gathered at the entrance into EU territory. Turkish President Recep Tayyip Erdogan raised the stakes today and vowed to allow refugees to travel to Europe from Turkey which he said can not handle new waves of people fleeing Syria. <br />'' <br />'' He said 18,000 migrants have crossed Turkish borders into Europe after the country opened the doors for them to travel. Turkey's decision followed a deadly attack on Turkish troops by Syrian government forces in northern Syria this week.<br />'' <br />'' At least 33 Turkish soldiers were killed in a bombardment in Idlib, the last Syrian province where Syrian rebel groups hold significant territory.<br />'' <br />'' Syrian government forces, supported by Russia, have been trying to retake Idlib from jihadist groups and Turkish-backed rebel factions.<br />'' <br />'' Turkey is hosting 3.7 million Syrian refugees, as well as migrants from other countries but had previously stopped them from leaving for Europe under an aid-linked deal with the EU.<br />''  <br />