The explanation might be simpler. He still needs to play, in some way, to a domestic audience. The fall of the USSR was objectively bad for a large part of th

The explanation might be simpler. He still needs to play, in some way, to a domestic audience. The fall of the USSR was objectively bad for a large part of the Russian population. Their economy and quality-of-life metrics have never really returned to pre-1991 levels. Their geopolitical relevance has been degraded, and Western institutions have nibbled away at their sphere of influence. They've lost millions of square kilometres of territorial holdings that date to Imperial times. He needs to perform some action to prove he's delivering something, and a stilted "you bait us long enough and we'll bite back" response might well fit, especially if they're already on a "the West is encroaching on our motherland" narrative. I still believe that if the Ukraine had made some token concession-- for example, offering a binding secession referrendum in the Donbass, that would have given Putin the bacon he needed to bring home without an actual war.