Russia is going to want a very good explanation how and why this guy was allowed to get that close and why he was not properly vetted. If they find Ankara dropped the ball, they will extract a pound of flesh. If the Turks can show that there was no inkling that he was going to do it, then it will be a point where they can work together. Russian tourism to the region is going to dry up again. Part of the Turkish problem is that they have courted the Islamist's, but as always they bite the hands that feed them.