Kobane/Kobani in Syria next to the Turkish border and has for a couple of months now been under assault by SIS.
There has been immense international pressure on Turkey to intervene and when it didn't, mass accusations that it was aiding ISIS.
It has often been stated that Turkey is often a route used by westerners to get into Syria/Iraq and potentially join ISIS. Further "damning" evidence against Turkey is that potentially around 400 Turks have joined ISIS.
What is often ignored when quoting this number is that there are more suspected britons (500) of having joined ISIS that Turks (400) even though Turkey is a Muslim country and is right next to the theatre of operations.