Okay, you've explained it better than anyone else has to me. It makes
more sense, but it doesn't make complete sense. I remember just prior to the invasion Putin was threatening to invade if Ukraine didn't do something or other. It might have been making an announcement renouncing the idea of NATO membership or something.
I just recall that at the time, it seemed silly to me. Maybe that's because I don't look at things the way a paranoid Russian would.