My concern about terrorism in Turkey stems from the apparent fact that there 7,500 migrants on Kos now. So that is 7,500 people who managed to travel through Turkey, unchallenged and unquestioned, to get all the way to the Datca/Bodrum tourism area for the short hop across the sea to Kos.
If 7,500 can move around Turkey en masse/in steady streams with no visa, kimlik or approval to be there, I reckon ISIS personnel pretty much have the run of the place whenever they want it.