“This can be a confusing question in this context because Russian President Vladimir Putin and the Russian Foreign Ministry have given multiple conflicting and in some cases mutually contradictory answers for why they are proceeding as they are.”
The short answer to why Russia invaded is that Putin wanted to. Devereaux, a military historian, admits he isn’t a Russia specialist and still explains it better than cable news. The Kremlin’s shifting justifications are cover, not reasons. When a government gives five contradictory answers, none of them is the answer.