That’s what the Putin war is all about.
The Ukrainian buffer"
That's pure nonsense because Russia would need no "buffer zone" and could make a European invasion literally impossible had Putin simply done what his predecessor Yeltsin intended, and western leaders like US Pres. Clinton urged him to -- join NATO.
But Vlad the Invader didn't want to join NATO (and thus guarantee peace) because he wanted, and still wants, to restore the Old Soviet or Tsarist Russian Empire.
That meant, as we've seen, wars and threats against Russia's neighbors to rebuild the Empire and intimidate everyone else.
Vlad the Invader doesn't want a "buffer", he wants to restore the Old Empire.
That's what Ukraine is all about.