Arms Control Association: #ThisWeek in Nuclear History: The Soviet Union detonated its first nuclear weapon on August 29, 1949 at Semipalatinsk in the Soviet republic of Kazakhstan. Tests continued at the site until 1989 with little regard for their effect on the local people or environment. After the Soviet Union’s collapse in 1991, tests ended at the site and it was officially closed on Aug 29, 1991. The International Day against Nuclear Tests is now observed annually on August 29.

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