Maybe a newly militarised Ukraine in 2021 + Ukraine's Decree №117/2021 which included the key objective of the "de-occupation" of Crimea forced a decision on Russia - either be passive and risk getting surprised by a sudden attack by Ukraine to over run Crimea or to act first.
News from 2021: "Today, President of Ukraine Volodymyr Zelenskyy signed Decree №117/2021 of March 24, 2021 “On the Strategy of de-occupation and reintegration of the temporarily occupied territory of the Autonomous Republic of Crimea and the city of Sevastopol» on the decision of the National Security and Defense Council of Ukraine of March 11, 2021."
The prospect of the Black Sea being a NATO lake, controlled by the strategically placed Crimea under Ukraine / NATO control, and thereby strangling Russian trade and naval power could not be ignored.
The decades long build up to geopolitical checkmate for Russia was possibly very close in 2021.
The do nothing position had become very high risk for Russia. The current "disaster"? may be in their eyes better than the alternative.
That is how geopolitical chess works - the "board" and borders are not frozen move and counter moves are always occurring. Passivity means losing.
