I am baffled by Russia's decision to go balls deep in Ukraine. Is it satisfying to do it? Heck yes. But as @MarKoz81 has noted in his excellent analysis, the best case scenario for Russia is to become a nuclear equipped henchman of the PRC. Is it really worth it for Putin to go all in and jeopardize Russia's hope for greatness?
It was surprising to me too. I was hoping Russia would find a way out of this conundrum without triggering the invasion.
However, I think the US is to blame here. The day before Russia pulled the trigger, the US sanctioned the Nord Stream pipeline. I think that was the final straw. Russia didn't want to invade, but was forced to because of that move. They had to at least secure their South Western flank if their 'plan A' failed.
The key thing I'm looking at now is Europe's response. The word is that the EU is dragging its feet already on imposing sanctions. I'm hoping Germany sabotages the sanctions regime. If that works, Russia would be able to salvage its strategy of fracturing NATO, and it may even accelerate the fracturing.
p.s. I just quoted this article to @asif iqbal, it provides context. I've been following this drama for a decade now. Chomsky has been warning about this since 2008, when Bush first tried to get Ukraine inducted in NATO. The US has been pushing Russia to the limit and it forced it into this box: