"There is no doubt that ability to move backwards and forwards across the 550-mile long Syrian-Turkish border has been crucial to the growth of the jihadi movements in Syria since 2011. The thousands of foreign volunteers who have flooded into Syria have almost all come from Turkey. Even those unable to speak Turkish or Arabic have had little difficulty in making their way across. In many respects, Turkey has provided a safe sanctuary for Isis and Jabhat al-Nusra, playing a similar role as Pakistan does in support of providing safe haven for the Taliban in Afghanistan." "A Syrian rebel offensive led by Jabhat al-Nusra was allegedly masterminded from an operational headquarters inside Turkey and was the outcome of a closer understanding between Turkey, Saudi Arabia and Qatar." (thanks Amir)