Those were Russian missiles in Cuba. It wasn't Cuba it's self that had us worried. It was Cuba's alliance with Russia and what having that ally so close to your shores would mean. (In this case it meant a place for Russia to put missiles within striking distance of our shores.) Without Russia, Cuba would have been just about as much a threat to the US as a 3rd grader is to a UFC Fighter. Without the powerhouse of Russia behind them, the ability to throw a large stone or sharpened stick at us would have been a great achievement for Cuba. Russia's hand was far heavier in Cuba, then it was in Vietnam. China was really the "Big Bad" as it were, of that war.