Bernard at Moon of Alabama believes several things informed the Russian decision to invade:
- Zelinsky’s announcement in spring of 2021 that Ukraine would retake Crimea by force,
- Ukraine’s announcement in November 2021 that it would retake the Donbass by force,
- an increase in Febuary 2022 of cease fire violations and “explosions,” “most” coming from the Ukrainian side, and
- Zelensky February 19 speech at the Munich Security Conference that the Russians understood as a threat by Ukraine to acquire nuclear weapons.
The Russians decided they simply could not tolerate a “fascist” government with nuclear weapons on their border and that Ukraine was preparing for a new war in the Donbass. [Almost as though, on that latter point, the US in its current delusional state was giving assurances of some kind to Ukraine to which it had also been supplying weapons, training and money.]
 “Zelensky And The Fascists: ‘He will hang on some tree on Khreshchatyk.’” By b, Moon of Alabama, 3/5/22.