Why? Russia only looses and they know this. They would also be firing on their own separatists in the east.
So called "separatists" are also part of Russian forces. With all the rotations of separatist commanders from Russian "ex-military" over years, I would not call them separatists at all.
Like they lost after annexing Crimea?
I still cannot fully grok the answer to this single simple question:
What’s Russia gaining by invading Ukraine?
The same as Crimea; Putin thinks he can get away with it.
A buffer state between NATO. An outlet for nationalistic growth. A distraction for aging western countries already experiencing governance issues. A use for military money already spent. Europe broadly is unprepared for an extended conflict against Russia. There are lots of reasons…