Agree that they would have no trouble winning conventionally, but are you sure they know how that would end? A few years ago, I think consensus would have been

Agree that they would have no trouble winning conventionally, but are you sure they know how that would end? A few years ago, I think consensus would have been that Russia wouldn't annex a sovereign state or deploy military assets in support of a separatist movement. ... I think reality is a lot more complicated. If they decided to go for a big push, and realized they could hasten victory substantially by deploying a few low-yield tactical devices? The international community has proved nothing other than "It's easier to ask forgiveness than permission." Besides, in a hypothetical case of annexing all of Ukraine, does "Russia used some tactical nuclear devices" really look that much worse than the also-present "Russia invaded and annexed a sovereign state"?