@ORAC: FWIW, America has a variety of mil assistance missions in a great many countries. So the Russians have one ongoing in Syria. *shrugs* Given that their objectives overlap (at least in part) with the general Western objective of dealing with the ISIS group in that multi faction cat fight going on in Syria (and for that matter in Iraq) I don't see it as a problem.
It may in the long term be helpful (it may also make the mess somewhat messier): hard to say.