You need to learn history. We almost triggered WW-III by naval blockade of Cuba because we did not want USSR weapons 90 miles from our border. But Russia is not allowed to fight NATO members right smack on it’s borders?
Oh, so you think the Ukraine situation is similar to Cuba? Let's look at that for a second.
We never forbade Cuba from being a Russian ally. Cuba is perfectly free to be allied with Russia. What we objected to was the Russians putting nuclear missiles in Cuba. In fact, there were Soviet/Russian troops in Cuba for many years, and we accepted it as long as they weren't nuclear.
We have never threatened or proposed putting nuclear missiles in Ukraine, and it would be entirely possible for there to be an express agreement that we would not do so even if Ukraine became a member of NATO. Being an ally does not have to equate to housing nuclear missiles, and Cuba itself proves that point.
Ukraine even offered not to join NATO at all as long as it could get security guarantees from other countries, and Russia rejected even that. So this has never, ever been about Russia feeling threatened. This is about Russia wanting to keep Ukraine isolated so that it can use military force or the threat of force to turn Ukraine into a puppet state.
So your Cuba analogy falls very flat.