Nah, you just haven't been paying attention to recent events. Russia doesn't have any forces capable of closing the Black Sea. Belarus is sitting on the fence and while they provide Russia with some logistical support they're not interested in committing suicide by shoving their own small military into the meat grinder. Russia could probably kill a lot of civilians with chemical weapons but Putin still wants to capture Ukraine somewhat intact, and this would also likely trigger economic sanctions by neutral countries such as India. Russia has already made many attempts to assassinate Ukrainian government officials with very little success.

Russia is still dangerous but it's a pale shadow of the old USSR.