Turkmen rebels fighting against Assad, Chechen insurgents (although I think they're further east than this particular area), all kinds of things.

No Da'esh, however, so Putin really should stop pretending that's why Russia is up in the Syrian North West.

Russian state media is (for now) saying that this is strictly a Turkish provocation and not NATO.

The Turkish NATO meeting for later this week was called before this incident happened; they were going to discuss Russia's attacks on the Turkmen areas. I suspect that the downed plane will be the discussion topic now, though, eh...