Imagine a timeline in which the Pacific War went horribly wrong for a poorly prepared USA, the 3rd Reich kept most of continental Europe, and the Soviet Union barely hung on after the Germans took Moscow and killed Stalin. San Francisco was devastated by the Japanese A-bomb before the USA could complete their own belated nuclear weapons program without any help from Mosley's Britain. There's been no previous American involvement in a Vietnam War or a Korean War.
Now it's the 1960's, and the USA is sending soldiers to fight in the Central American War.
What's the counter-culture movement like? What sort of social unrest is happening?