did the USA interfere with the missile system that the Soviet Union tried to put in place in Cuba back in 1962? What business of it was the USA to interfere in that?
Under the Monroe Doctrine, it was damn well our business at the time, especially given the missiles the former Soviet Union had there, some of which could reach as far as Chicago & Detroit? I mean, I know we Americans can be slow on the international uptake at times, but dude, once we knew those missiles were there, they were going to leave one way or the other....and the way we got the Soviets to take them out of Cuba was the classic way a country deals with a pathological bully: you use enough force (or the threat of using said force) as a card to play in the hopes that your opponents sees that your serious and steps back from the brink.
As to Eastern & Central Europe, Worldwide...
and you don't think that Russia has self defense concerns about every NATO country around them building missile systems as the EU grows closer to Russia's boarders? Doesn't matter if you agree with it or not, what matters to world security is that Russia feels threatened and is prepared to defend itself if needed.
...what business is it of Russia's to tell its' neighbors what they can or can't do?
This is not the Cold War, where even the Soviets knew the "rules of the game" as they were, nor is the era of the Russian Tsars; you have sovereign countries - many of whom were formerly occupied by Russia at one point or another - that have made the clear and conscious decision to turn westward, to join with their Western Europe counterparts either as members of the EU or NATO (or both) and it pisses Vladimir Putin to no one because it means he can't re-create the former Eurasian sphere or influence that the former Soviet Union nor Tsarist Russia once had....so he has to do two things: (1) weaken Western Europe through covert means and (2) take territory from non-NATO/EU member states in the hopes that he can gauge what he thinks the West will do...
...well, I'm sorry, but if he thinks the West will back down in the East...he's got another thought coming; everything he does in that region, we can do to Russia elsewhere and there are a few things the West can do to express their displeasure towards Russia, but those are separate conversations for later.