Putin's #1 play in this is the hope that he can intimidate every neighboring nation that has not already joined NATO into being a pure Russia satellite state or risk invasion.
Just since Putin became Russia's leader, he's watched Poland, Hungary, Czech Republic, Slovakia, Slovenia, Romania, Bulgaria (oddly), Estonia, Latvia, Lithuania, Albania, Croatia, Montenegro, and North Macedonia all join NATO. Plus Bosnia, Georgia, and Ukraine all want to join. This is a massive L for Putin in terms of his pride as well as the degree to which he can bully these neighboring states.
He wants to end that shyt. He thinks that with a show of force now he can start winding back that expansion, tell future aspirants and even current members "fukk NATO, if you don't kiss the ring then I'll do the same to you and none of them will help", and widen his sphere of influence because he's feeling very isolated in Europe right now. It's a tight line to walk though because his power isn't infinite and many of his supporters don't really want to risk their already precarious state with more war, so he's trying to have it both ways - intimidate everyone into believing that Russia is the only nation that will truly employ its forces without actually having to truly employ its forces.