Nikolas Gvosdev gives another reason for Russia’s position on Syria:

A consistent question posed by U.S. policy makers is the basis of the loyalty the Kremlin is showing to Assad. Why can’t Moscow simply “cut a deal” with the revolutionary forces (assuming one could be brokered) and switch sides? If the Syria conflict existed in isolation, perhaps. But the steadfast support the Kremlin continues to provide to Assad—shielding the regime against stronger UN sanctions and providing its security forces with the wherewithal to try to suppress the uprising—is meant to reassure another group of leaders: presidents in the post-Soviet space concerned with their own successions.

It shouldn’t be so difficult for Americans to understand the Russian position. One of the most common arguments one hears from all sorts of American internationalists is that the U.S. has to keep reaffirming its support for a given ally or client so that the others do not begin to doubt U.S. commitments to them. Most of the time, this is an argument for perpetuating a particular client relationship or for maintaining a U.S. military presence in the region. This is arguably not a rational view, but it is one that major powers take all the time. It isn’t necessarily the case that a change in policy towards one client signals changes in policies elsewhere, and abandoning a relationship with a weakening regime is probably smarter over the long-term, but all major powers fear that giving up on one client when it is in trouble will be perceived as weakness by other major powers and as proof of the major power’s unreliability by their remaining clients.

One of the recurring, albeit false, attacks on Obama is that he has undermined or “sold out” various allies and clients around the world. These attacks have some political value because hard-liners are inclined to see any hint of wavering in support for an allied or client government as a sign that the current leadership is embracing American “decline” and “retreat.” Considering how relatively few clients Russia has around the world, each one would have greater value to Moscow than any one client state would have for the U.S. Simply being one of those few clients would make it more important to Russia than the interests that Russia actually had in the country alone would suggest. The U.S. has a great number of allies and clients (I would argue that we have far too many to be able to fulfill our commitments to all of them), but it is not politically feasible to cut off support to any of them once it has started. We should remember that the same bias in favor of existing policy is just as strong or stronger inside other governments.