In case of USSR/Russia, nuclear weapons serve their purpose perfectly.
Seeing as how the Soviet Union doesn't exist any more, that's obviously not true.
It is true that we didn't destroy the USSR militarily. Doesn't matter. We destroyed it with other weapons instead--and the USSR didn't have the gumption to fire nukes in retaliation.
We were involved IIRC in about 7 major military conflicts on our territory in first half of XX century and zero in second half.
That holds true for a bunch of other nations in Europe as well--and none of them had nuclear weapons. In addition to beating up on Russia, various nations in Europe also had a long history of beating up on
each other. In the second half of that century, that stopped. At least, in Europe.
World War II caused a fundamental shift in thinking in Europe and the United States; we don't conquer for territory any more. Yes, the rest of Europe decided to stop beating up on Russia--but nukes aren't the reason. The change in mindset is.

You don't have a slightest idea about state of Russian army today.
Its nuclear potential is arguably the best in the world, and certainly comparable to the American one.
That's true of Russia's
civilian nuclear program.
Russia's
military nuclear program is a mess.
It was not Cuban decision. Khruschev removed Soviet missiles from Cuba, when Kennedy agreed to remove Jupiter missiles from Turkey in exchange. You obviously know this.
Oh, yeah. I stand corrected.
THE SOVIET UNION folded.
He simply didn't want to start WW3 over Cuba issue
Exactly. The United States looked Russia in the eye and said "go ahead, push The Button, I dare you" and Russia blinked. Russia's nuclear deterrent failed. The strategic equation is kind of assymetrical in that way; U.S. nuclear deterrent does work on most external threats, but foreign nuclear deterrence against the U.S., surprisingly, does not.
