It was the cold war, and the US had already put nukes into Italy and Turkey, well within range of Moscow.
In such a game-theoretical standoff, the USSR had had to react – to keep the balance of power.
It’s a completely crazy situation, and I’d consider both sides of the conflict as Evil, but I’m not sure why so many people try to claim the US was Good, while the USSR was Evil. Both stood for some good, and some very bad principles.
I edited the comment to reduce the conflict potential, but keep the general idea of it.