You might want to take a look at a map and ask why the **** the organization is called NATO and why the organization still exists after Russia disbanded the Warsaw Pact. Seriously, what is the point of NATO other than to surround Russia with armed nations?
It exists because Russia has a history of imperialism in eastern Europe, and the countries of those regions seek protection from it.
Russia did not disband the Warsaw pact out of charity or goodwill. They did it because they lost the power struggle of the Cold War and were no longer strong enough to keep it together.
Whether cold or hot, losing wars has consequences, and Russia's loss of influence to the US in eastern Europe is part of that.
The war in Ukraine is more about resentment toward the US and attempting to restore Russian national pride and power in eastern Europe than anything else.
Somewhat like the Germans in the 1930s in response to losing WWI and the loss of territory, pride and power that resulted from it.
If China armed Mexico, Canada, and Cuba with massive amounts of weapon and put hundreds of thousands of Chinese troops on the Mexican and Canadian borders, you would be fine with that I guess.
We have nowhere near hundreds of thousands of troops near Russia's border. We've been cautious about our military presence in NATO countries because we know it would be a provocation for the Russians.
Until recently, we had the same approach toward the types of weapons we deploy in eastern Europe, but that has been changing since Russia's aggression in Ukraine.
We were offering no significant military support to Ukraine until the Russians starting annexing parts of it in 2014.
You like to peddle the Russian line that Yanukovych's ousting was a US coup, but he was not popular with many Ukrainians and he was playing with fire when he refused to sign the EU relations bill that the Ukrainian legislature had passed.
Play stupid games, get stupid prizes.