The Cold War and the fear of nuclear war
The Cold War was a dispute for world superiority between the United States and the Soviet Union after World War II (1939-1945). It is called the Cold War because it is an intense economic, diplomatic and ideological war waged by the conquest of zones of influence.
The dispute split the world into blocks of influence of the two superpowers and sparked an arms race that spanned 40 years. With different economic and political systems, the US and USSR put the world under threat of nuclear war, creating weapons of sufficient power to blow up the entire planet. The US took the leadership of the so-called free capitalist world, and the USSR of the communist world.
Churchill, Roosevelt and Stalin at the Yalta Conference, 1945.