Not to mention that being ethnic anything does not give you the right to start a war. I suggest you imagine a situation where ethnic non-Russians, in Russia, decide to break off a piece. Does Russia have the right to ruthlessly end that? Because it wouldn't even be a question.
Phillip Karber, an American military scholar, has been to the front many times to study Russian military equipment and tactics there:
https://mwi.usma.edu/video-dr-phillip-karber-ukraine-russian...