I have to wonder..how far will Russia go with these ships in the MED? And who's going to blink first?
I think the Russians are there to ensure that the US does not get the idea of doing anything like regime change or decapitation. Assad will have taken measures to avoid it himself and will be secreted away somewhere, very hard to hit in any case.
If the US ends up doing what I believe they will...that is launch 100-200 Tomahawks at military targets within Syria related to the ability to attack with chemical weapons, then those Russian ships will sit there and not take any active part whatsoever. They will probably be out to sea (the combatants) where they could maneuver and more ably defend themselves if necessary. There will be some amphibs, support ships, etc. left in port and these will ensure that the port facilities themselves are not targeted.
Such a US attack as this is meant to simply send a strong message...and is being conducted purely to make Obama look credible when he gives a warning. However, it will not amount to very much militarily as far as the civil war goes at all. It will cause damage to Syrian units associated with potential chemical deployment (ie. Air Force units, artillery units, radars for the air force, etc.) so will be costly to the Syrians, but not fatal by any stretch, and not of much impact (as I say) to the civil war.
If that is how it goes, then at the end, Obama will puff out his chest and strut around like he is come kind of Peacock and the US press will back him in that. Putin will complain loudly and seek to adopt some sort of political and foreign relations penalty for Obama, and the civil war will continue as before.
Now, if Obama tries to go after the Syrian C&C in a serious way and goes after Assad, or if the campaign continues for weeks and is a clear effort to seriously degrade Syrian military efforts across the board in preparation for an air campaign, then I expect the Russians would reach a point where they would potentially become actively involved, probably starting off by using their vessels to actively jam, decoy and deter strikes first.
Or, if Iran goes crazy and mounts a serious attack on Israel, then all bets are off and a regional war could easily break out.
Also, if Syria mounts a strong defense and launches Yahkont missiles at US ships, or mounts serious air attacks against US vessels, this too would cause things to escalate.
But my bet is, as long as certain parameters are maintained by the US strike, as mentioned above, Putin will ensure that Assad does not do anything rash and advise him to just weather the storm.
Anyhow, that's how I see it going.