ANALYSIS: How Turkey was forced to fall in line over Syria

"Unlike the US, Turkey actively sought to remove Assad from power through granting support to multiple armed groups in Syria. It also initially saw in the rise of IS a potential opportunity to quickly get rid of Assad and in the Syrian conflict an excuse to crack down on the Kurdish Workers Party (PKK) in the south along the Syrian border.

However, its laissez-faire approach to its Syrian border, which allowed thousands of foreign fighters to cross into Syria from Europe and elsewhere to join IS and other groups, put Turkey under pressure from Europe as well as the US who began to label it as an agent of instability. Increased Turkish monitoring of the border came too late as IS had by then established presence on Turkish soil and began a series of terrorist attacks in different Turkish cities."