Russia absolutely has the air power to pull it off, you clearly haven't seen Syria.

My guess is that they have, correctly, anticipated that mass casualties of white civilians would play very badly internationally and domestically.

e: I'm downvoted.. for what? It's obvious that the ethnicity of the victim matters for both domestic and international perception, all you need to do is look at a bit of media coverage of reporters bemoaning that this is happening to "blue eyed, blond haired" people or in the "civilized world." There is a different standard for what sort of casualties are considered acceptable.