I mostly agree with what Streetwise Professor has to say about Russia’s involvement in Syria but I propose a conspiracy-theoretical addendum.
First, why did Russia consent to the nuclear deal with Iran despite the downward pressure it would exert on the oil price? Were there any rewards promised for its cooperation?
Second, what is the Kremlin’s maximum set of goals in this Middle Eastern campaign? Does it include large-scale destabilization in the Middle East, especially of certain Sunni autocracies?