In which John Green teaches you about the Cold War, which was the decades long conflict between the USA and the USSR. The Cold War was called cold because of the lack of actual fighting, but this is inaccurate. There was plenty of fighting, from Korea to Viet Nam to Afghanistan. The Cold War started, in short, by growing out of World War II when the Soviets occupied eastern Europe and the US supported western Europe. This setup would spill across the world, with client states on both sides.