Exactly why the Russians will veto any UN resolution that even hints at regime change in Syria - they have invested way too much in Tartus and will never, never give it up.
What is to stop Russian (or Iranian) “advisers” from being sent to Damascus to help quell that insurrection of “terrorists and Zionists”?
There are other reasons why the Russians support the Syrian regime even though its been bumpy.Syria for the past few years has reached out to Russia to obtain modern weapons that included many modern anti-tank and anti-air missile systems that will further improve its combat capabilities. It will be difficult for advisors from Tehran to break off ties to Damascus. They both support and main suppliers of both Hezbollah and Hamas.