On 6 August 1945, the USA dropped an atomic bomb on the Japanese city of Hiroshima. The blast devastated an area of five square miles, destroying more than 60 per cent of the city’s buildings and killing around 140,000 people. Three days later the USA dropped a second atomic bomb on the Japanese city of Nagasaki, killing around 74,000 people.
The official US justification for the dropping of the two atomic bombs was to force the Japanese government to surrender, which it did on 14 August 1945. Some historians have speculated that the bombs might also have had another purpose - to send a warning to the Soviet Union about the strength of the American military.
Whatever the intention, the USA had changed the nature of warfare, and for the remainder of the Cold War the threat of atomic weapons and nuclear war would be a constant theme. Stalin himself remarked that future wars were inevitable and the Soviet Union now began its own programme of atomic research. American 'nuclear hegemony' would not last long.