Nothing new here.
Look at a map. ISIS is geographically surrounded by Kurds, Iraq, Israel, Assad controlled Syria, and Hezbollah controlled Lebanon, and.............. Turkey.
Now, everyone but Turkey officially wants ISIS exterminated.
Hmmmm. Turkey says they want ISIS defeated, yet, other than Turks, whom could ISIS have sold all their oil in order to finance themselves?
What other pathway could ISIS fighters get in and out of ISIS territory to the rest of the planet, but through Turkey?
What other country surrounding ISIS has been relatively terror-attack free from ISIS, but Turkey?
Earth calling Captain Obvious......
Yes, sir. It does not even require Captain Obvious to figure that one out.