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Events on Wednesday 12 August 1953 1
1953Soviet Union Tests First Hydrogen BombRDS-6s detonated at SemipalatinskThe Soviet Union detonated its first thermonuclear device, codenamed RDS-6s, at the Semipalatinsk Test Site. The design, developed with contributions from physicist Andrei Sakharov, used a layered fission-fusion configuration. The test significantly escalated the nuclear arms race with the United States.