Being comfortable in your neighborhood is not a delusion, it's a core priority most nation states will be willing to go to war over. If you are American, then you will likely not understand this because America is blessed with wonderful location: it does not have to contend with dozens of possibly unfriendly neighbors bordering it, which is a luxury that Russia, China, and India do not have. They are huge landmasses having long borders with many, many different neighbors who are not all friendly. America has thousands of miles of ocean from its bigger rivals, which all but rules out massive land wars and even air wars. Only a blue-water navy can challenge America, and even then the Americans can take the fight to the littoral states of countries like China if they have beefs with them. Can you imagine that with America?

It's the same thing with Russia: Putin has struck a deal with Xi that allows him to move his military assets from the east to this theater, because he feels that it's a strategic imperative to 'clear the neighborhood'.

Russia has given up land and trapped foreign invaders, including Napoleon and Hitler, but it has done so at a huge cost in blood and treasure. From Russia's perspective, it's far more cost-effective to have weak client states that do their bidding on their hard-to-defend flanks, than to have strong, democratic, independent states that can ally themselves with their archenemies.