The video of the shooter has the guy shouting "Allahu Akbar", then followed by what I think is Turkish but given the target, and if they're right that he shouted something like "for Aleppo", he may be Turkmen. Recent Turkey-Russia dispute over Syria began because of Russia's bombing of Turkmen anti-Assad rebels that recieved support from Ankara. And where are they based? Well...Xenophon wrote:Russian Ambassador to Turkey was shot in Ankara.
https://en.wikipedia.org/wiki/Syrian_Tu ... des#Aleppo
If it is that particular group, or one allied with it, that's probably going to sour Turkish-Russian relations a teeny, tiny bit.