[handedness]

Many analysts of very sane mind imagined exactly that war 20 years ago, or longer.

The geopolitical fact is that Russia lacks strategic depth, which has bitten it badly multiple times in the past. From their view, that's something to be remedied to prevent future occurrences.

For Russia to gain strategic depth, there are a few lines which it needs to control. There are ~6-10 gaps, depending on how you count them, and on what net importance/counter-productiveness you assign to some of the more marginal and fraught ones. Holding any is better than holding none.

The big surprise is that Putin left Ukraine so late, when many of his best-trained ex-Soviet personnel had already died. Had he done it even just a few years earlier, the outcome would have likely been very different. The only analysts who thought it wouldn't happen thought so precisely because he left it too late.

Regardless, the best time for Europe to get serious about this war was before it started, unfortunately, and there was ample warning.

I hope you can stay safe so near to it.