Russians aren't eager to endure heavy casualties in Putin's adventures. Or even many at all, it seems, at least abroad (even in the "near abroad"):
Russia learned the hard way in Ukraine that even among their most ardent nationalists there were few men willing to fight. Back in Russia the eager fighters are few in number and many are still needed in Ukraine (to keep the Ukrainian “rebels” in Donbas going) and the Caucasus (to keep pressure on Islamic terrorists down there). Russia is also increasing pro-war propaganda. But it has already found in Ukraine and Caucasus that this sort of encouragement has little impact the closer you get to the combat zone and none at all when you start shipping bodies back to families. So Russia is keeping troop levels (and friendly casualties) low in Syria and cash inducements as high as they need to be.
Yes. That is the vulnerability of Russia as I noted early in the Ukraine Crisis:
I'm not sure what could impress Putin with the need to halt his aggression against Ukraine and deter further aggression other than more dead Russian soldiers.
Not only is Russia's civilian population not eager to endure casualties for Putin's wars, but Putin needs decisive low-casualty wins over his weaker enemies to burnish his reputation.
The lightning takeover of Crimea provided that.
The slow slog in Donbas is not providing that.
Syria has so far provided that but the war isn't over. The danger of having to decide between enduring Russian casualties to save Assad or retreating is still high for Putin. Which is why Putin is counting on Lavrov to work Kerry by stroking his ego in order to get a grand deal that saves Assad while getting America to join Russia in paying the price for saving Assad.
And even though Putin is organizing his own army that should be personally loyal to Putin rather than to the state, does this erase the need to endure few casualties for either prestige or public support purposes?
Or does it just make it easier for Putin to roll the dice and see whether the outcome is breaking NATO or becoming leader of the Grand Duchy of Moscow?
Putin could easily believe that possession of lots of nuclear weapons makes the odds of the former greater and the latter lower, making it a good gamble to restore Russia (and ensure his place in history) before demographic decline in Russia, Chinese military modernization, and a rethink in NATO about maintaining significant military power make such an achievement impossible.
One of the great achievements of Bush 41 was managing Russia's loss of empire--twice, in 1989 and 1991--without a nuclear disaster being the result.
Yet don't think that the empire is gone--it's just smaller.
If Putin breaks Russia again by over-stressing its limited capacity, will we be that fortunate a third time?