Yeltsin was a drunk. No sober Russian leader is going to allow NATO in Ukraine.
Putin is saying loud and clear, Russia is willing go to war over NATO in Ukraine, and he's giving a clear demonstration that he is not bluffing, and that yes, he is "asshole" enough to follow through on it. That's why he didn't stop with taking Crimea. He is sending a message, that even without Crimea, he is not going to allow Ukraine to join NATO.
And that's why he won't deescalate anything. Nothing is going to be off the table until NATO expansion is off the table.
First, that's an issue for Ukraine to decide.
NATO wasn't planning on expanding into Ukraine. (Also, EU != NATO.) NATO was starting to look ever more irrelevant, and now Putin's antics has given NATO a new mission and newfound support. It's caused Finland, a non-NATO country on Russia's border, to consider joining NATO. Hell, he's pushed Ukraine even further towards the West and quite possibly permanently closed the door on bringing Ukraine
willingly back into the fold. So if Putin's desire was to limit NATO expansion, it sure as hell looks like it's going to backfire.
And why is Putin so afraid of Europe? Hm? It's not like Western Europe is planning yet another invasion of Russia. They're friendly, and they're peaceful. There has been a lot of progress in EU-Russia relations, like growing economic ties and even Russia's participation in Eurovision. So what if Ukraine signs an EU association agreement? How the hell does that threaten Russia? How the hell is that against Russia's interests? If anything, it would be
good for Russia's economy if her neighbors were to modernize.
Well, let me tell you why Putin doesn't like the EU: It's because the EU is a threat to
him. Not to Russia. But to him. Personally. Because the EU advocates for political freedom. For free speech. For the rule of law and anti-corruption.
That is what's so appealing to the Ukrainians. They're fed up with their country having languished for two decades while former Warsaw Pact countries that embraced the West like Poland or the Czech Republic are becoming increasingly prosperous. They are fed up with the rampant corruption and the lack of rule of law that Russia represents (and before Crimea becomes too happy about being a part of Russia, maybe they should look at South Ossetia, where well over half of the resources that Moscow poured into it after the Georgia conflict was simply wasted or lost to corruption and where things are pretty much as they were before--that is to say, bad).
Ukrainians have a lot of common history, culture, and ancestry with Russians, so it's not like they hate the Russian people or anything like that--they want out of the Moscow orbit because of what Moscow represents
politically. You can bet your ass that if Russia wasn't ruled by a megalomaniac Putin or by a drunk Yeltsin but was instead ruled by someone who's actually fair and competent, Ukraine would not be so eager to distance herself.
The problem, ultimately, is Putin. He has delusions of grandeur. He wants power. If he was truly acting in Russia's interests, he'd accept the international community's invitation to participate. But he's not. He's acting
against Russia's interests in order to
preserve his own power. He's rekindling old Cold War conflicts not because the EU or NATO somehow screwed Russia, but because it's a convenient way to solidify his power base and to redirect malcontent. In short, he's behaving no differently than the Kims of North Korea. I'm sure you'll agree that whatever the North Korean leader does is not in the interest of NK or her people, but purely in the interest of sustaining their hold on power. And that, to a much lesser extreme, is Putin.