On January 7th 1953 President Harry Truman announced that the US had tested a hydrogen bomb, hundreds of times more powerful than the atomic bombs dropped on Hiroshima and Nagasaki in 1945. The US bomb had in fact been tested on Eniwetok in the South Pacific on November 1st 1952. The Russians had begun their own programme of nuclear development in 1948 but were several years behind the Americans and tested their first effective Hydrogen bomb on November 22nd 1955. The British tested their hydrogen bomb in May 1957, by which time the nuclear arms race was well under way.
Technically the hydrogen bomb is a fusion device, whereas the atomic bomb is a fission device. The atomic bomb releases energy by splitting heavy atoms of either …
Editors. "Hydrogen Bomb tested". The Literary Encyclopedia. First published 27 March 2005
[http://www.litencyc.com/php/stopics.php?rec=true&UID=1531, accessed 21 January 2017.]