But even though Mutually Assured Destruction prevented direct conflict, there was plenty of hot war in the Cold War. The Korean War saw lots of fighting between communists and capitalists, as did the Vietnam War. I mean, these days we remember the domino effect as silly paranoia, but after Korea and especially China became communist, Vietnam's movement toward communism seemed very much a threat to Japan, which the US had helped remake into a vibrant capitalist ally. So the US got bogged down in one of its longest wars while the Soviets assisted the North Vietnamese Army in the Viet Cong. But then we paid them back by supporting the anti-communist Mujahideen after the Soviets invaded Afghanistan in 1979. Of course, as we now know, nobody conquers Afghanistan. Unless you are the Mongols.