1950
January 27 - Klaus Fuchs confesses that he gave atomic secrets to the Soviets while working at the Manhattan Project.
January 31 - President Truman announces the decision to proceed with development of the Hydrogen bomb.
1951
January 27 - The first nuclear test occurs at the Nevada Test Site.
June - First British nuclear reactor goes critical.
Julius and Ethel Rosenberg are convicted and sentenced to death for passing information on atomic weapons to the U.S.S.R.
1952
September - A second U.S. nuclear weapons laboratory is established in Livermore, California.
October 3 - First British atomic bomb, "Hurricane", was tested at Monte Bello Islands, Australia, with a yield of 25 kiltons.
October 31 - U.S. explodes first thermonuclear or fusion device, "Mike", at Eniwetok Atoll. It had a yield of 10.4 megatons.
1953
August 12 - First Soviet layercake design bomb exploded on a tower in Siberia. It was not a "true" hydrogen bomb.
1954
March 1 - The first deliverable hydrogen bomb is tested at Bikini Atoll. "BRAVO" had a yield of 14.8 megatons. Radioactive fallout affects local islanders and a nearby fishing boat.
April 12 to May 6 - Hearings regarding Oppenheimer's loyality cause him to lose his security clearance.
1955
The U.S.S.R. deploys two strategic bombers, Bear and Bison.
The United Kingdom announces the decision to develop thermonuclear weapons.
November 22 - First true fusion device test by the Soviet Union, it had a yield of 1.6 megatons. The development was lead by Andrei Sakharov
1957
May 15 - First British H-bomb exploded at Christmas Island. The yield was between 200 - 300 kilotons. It was less than expected.
September 19 - First underground nuclear test, "Rainier", occurs at the Nevada Test Site. It had a yield of 1.7 kilotons.
November 8 - Britain's first truly successful thermonuclear bomb test. The bomb had a yield of 1.8 megatons.
October - Fire destroyed the core of a reactor at Britain's Windscale nuclear complex, sending clouds of radioactivity into the atmosphere.
1958
July 2 - President Eisenhower signed amendments to the 1954 U.S. Atomic Energy Act which opened the way to a bilateral agreement between Britain and America on nuclear weapon design information.
November, 1958 to September, 1961 - U.S., U.K., and U.S.S.R. observe an informal moratorium on nuclear tests.
1959
June 9 - The first U.S. Polaris nuclear missile capable submarine enters into service.
October 31 - The U.S. deploys the first operational intercontinental ballistic missile (ICBM), the Atlas D.
