> It's one of several hard to defend routes into Russia. Russia needs Ukraine as a buffer.
No, Russia doesn't need it.
I'm sure you're correct that Russia believes this, but the reality is that no one actually wants to invade Russia, and no one has wanted to invade Russia for a very, very long time. All Russia's neighbors have only been worried about invasion and oppression from Russia, ever since the end of WWII.
Somehow, the Russian people seem to collectively have a weird paranoid victim mentality, thinking they're always under threat of invasion, when in reality everyone just hates them and wishes they'd keep to themselves. They think they're entitled to controlling other neighboring countries for their own defense, but they never give a thought to those countries' defense. Somehow, places like Poland and Sweden these days are able to not worry about being invaded by their (non-Russian) neighbors, so all the other borders within Europe are completely undefended. Maybe if Russia tried being friendly with other nations instead of constantly threatening them with military action, they could have a peaceful coexistence too.
Maybe they're still stuck in 1930s mentality. Back then, Hitler really did want to invade Russia (and did), along with Poland and a bunch of other countries.
However, the world has moved on in the last 80 years. Germany is part of NATO now, Poland and Germany are friends (and France, Netherlands, etc.), and no one is worried about invasion from Germany any more. Somehow, the people of Russia never got past the mindset they had back when Hitler tried to invade.
Maybe. Or maybe they’re assuming everyone else is itching to invade and subjugate Russia, because Russia would and continues to do so to all their neighbors at the slightest opportunity. They can’t conceive that the rest of the world really has moved beyond such idiotic imperialist behavior.
* Ukraine historically had been their bread basket
* It's one of several hard to defend routes into Russia. Russia needs Ukraine as a buffer.
* Eastern Ukraine has lots of mining and industry Russia needs that were critical to the UDSSR economy as well.