A nuclear arms race developed during the Cold War, an intense period between the Soviet Union and the United States and some other countries. This was one of the main causes that began the cold war. On both sides, perceived advantages of the adversary, such as the "missile gap" led to large spending on armaments and the stockpiling of vast nuclear arsenals. Proxy wars were fought all over the world in the Middle East, Korea, Vietnam in which the superpowers' conventional weapons were pitted against each other.
Klaus Fuchs was a German theoretical physicist and atomic spy who, in 1950, was convicted of supplying information from the American, British, and Canadian Manhattan Project to the Soviet Union during and shortly after the Second World War. While at the Los Alamos National Laboratory, Fuchs was responsible for many significant theoretical calculations relating to the first nuclear weapons, and later, early models of the hydrogen bomb.
The second Red Scare occurred after World War II (1939–45), and was popularly known as "McCarthyism" after its most famous supporter, Senator Joseph McCarthy. McCarthyism coincided with increased popular fear of communist espionage consequent to a Soviet Eastern Europe, the Berlin Blockade (1948–49), the Chinese Civil War, the confessions of spying for the Soviet Union given by several high-ranking U.S. government officials, and the Korean War.
On June 25, 1950, the Korean War began when some 75,000 soldiers from the North Korean People's Army poured across the 38th parallel, the boundary between the Soviet-backed Democratic People's Republic of Korea to the north and the pro-Western Republic of Korea to the south.
"Midnight" has a deeper meaning to it besides the constant threat of war, There are various things taken into consideration when the scientists from The Bulletin of the Atomic Scientists decide what Midnight and Global catastrophe really mean a particular year, They might include “Politics, Energy, Weapons, Diplomacy, and Climate science.” Members of the board judge Midnight by discussing how close they think humanity is to the end of civilization. In 1947, during the Cold War, the Clock was started at seven minutes to midnight. The Clock's setting is decided without a specified starting time. The Clock is not set and reset in real time as events occur; rather than respond to each and every crisis as it happens, the Science and Security Board meets twice annually to discuss global events in a deliberative manner. The closest nuclear war threat, the Cuban Missile Crisis in 1962, reached crisis, climax, and resolution before the Clock could be set to reflect that possible doomsday.
In most of the states of the North Atlantic Treaty Organization, such as the United States, the United Kingdom and West Germany, as well as the Soviet Bloc, and especially in the neutral countries, such as Switzerland and in Sweden during the 1950s and 1960s, many civil defense practices took place to prepare for the aftermath of a nuclear war, which seemed quite likely at that time.