The Soviet side, however, is a different story. One of the lessons learned after the fall of the Berlin Wall was that, although NATO considered nuclear weapons use in an invasion a possibility, to the Soviets, their use was a foregone conclusion. Every Soviet war plan unearthed from Warsaw Pact archives assumed liberal use of nuclear weapons — up to 300 or more.
Kyle Mizokami in The Lovely Little Town That Would Have Been Absolutely Screwed by World War III
It’s amazing how close we truly were to nuclear war for so long, and that we managed to avoid it. The Real Cuban Missile Crisis is well worth reading as well, should you want to drive the point home.