The Russian annexation of Crimea had at least some ambiguity. Yes, it was illegal, but Crimea used to belong to Russia, it had majority Russian-speakers, and there was no violence on any significant scale during takeover. The question was, if they are taking over your territory, why don't you fight back? The answer is obviously complicated (and for the record I fully support Ukraine, and I think Crimea and all other occupied territories must be returned to Ukraine). Russia has succeeded, to some extent, making it a "one-of" issue. Now, of course, they've completely destroyed their previous position, it turns out Crimea is not special, they basically try to annex any territory they have any sort of control over.