Cold War
July US President Truman told Soviet leader Stalin about the US development of an atomic bomb.
  August 6 United States dropped atomic bomb on Hiroshima.
  August 9 United States dropped atomic bomb on Nagasaki.
1946 March 21 USE created Strategic Air Command (SAC). Its main concern was the potential use by the USA of nuclear weapons.
  June 14 Bernard Baruch presented the Baruch Plan to place nuclear materials under the control of a U.N. agency equipped with inspection powers and exempt from the great-power (Security Council) veto. The Soviet Union objected because the agency would be dominated by USA and was not willing to surrender veto or accept inspection within the Soviet Union.
  July 1 Atomic bomb tests at Bikini Atoll in the Pacific.
  August 1 Atomic Energy Act.
1949 August USSR carried out successful test of an atomic bomb.
1950 January 31 Truman approved the development of the hydrogen bomb, far more powerful than the atomic bomb.
  June 25 Korean War began.
1952 November 1 Hydrogen bomb exploded by the US Atomic Energy Commission (AEC) at Enewetok, Marshall Islands.
1953 August 14 Soviet Union exploded its own hydrogen bomb.
1954 May 1 Soviet Union unveils the M-4, its first jet-engine propelled long-range bomber, capable of carrying nuclear weapons.
1955 June 15 Nationwide civil defence exercises began in USA to prepare against nuclear attack.
  June 29 USA began deploying B-52 bombers permanently in the air. This meant that they were able to launch a nuclear attack anywhere in the world.
  July Fear of a "Bomber Gap" ensues after the Soviets fly Bear and Bison long-range bombers multiple times past American visitors at an air show, causing an exaggerated assessment of Soviet inventories. There is now strong evidence to suggest that the US government knew that the bomber gap was a myth.
  July 18 Geneva Summit Conference: Eisenhower, Khrushchev, and Eden discuss disarmament and European security. Eisenhower proposes "Open Skies," which would allow aerial reconnaissance of each other's territories.
1956 November 17 Commenting on nuclear technology, Khrushchev declared "We will bury you" to Western diplomats.
1957 August 26 Soviets successfully test their first Intercontinental Ballistic Missile (ICBM)
  September 19 First underground nuclear test place took place in a mountain tunnel near Las Vegas.
  October 4 Soviet Union launches Sputnik, the first satellite to orbit Earth
  November 3 Soviet Union launches Sputnik 2, which carries the first living creature (a dog) into space.
  December Gaither Report to US government alleged that the Soviet Union had achieved superiority in long-range ballistic missiles leading to fears of a "missile gap." Similar to 'bomber gap'.
  December 17 ICBM: First successful test of US Atlas ICBM.
1958 January 31 First U.S. satellite, Explorer I, is launched into orbit.
  March 30 Soviet Union suspended atmospheric nuclear testing.
  June 30 US developed Nike-Hercules missile, with increased range capabilities.
  October United States and Britain suspended atmospheric testing.
1959 September 9 Atlas ICBM becomes operational.
  September 13 Soviet spacecraft reaches the moon and crashes there.
1960 March Cuban exiles: Eisenhower agrees to CIA proposal to train Cuban exiles to subvert Castro regime.
  May 1 U-2 reconnaissance plane shot down over central U.S.S.R. Pilot Gary Powers is held by the Soviet Union. The incident was announced by Khrushchev on May 5.
  May 16 East-West summit conference in Paris collapses over U-2 incident.
  May 24 United States launches Midas II satellite for military reconnaissance purposes.
  July 20 United States fires first ballistic missile from a submerged submarine off Cape Canaveral.
  August 19 U-2 pilot Gary Powers sentenced by the U.S.S.R. to ten years in prison; he is exchanged for a Soviet spy in 1961.
  November 8 Kennedy elected president.