On August 23, 1953, the Soviet RDS-4 "Tatyana" tactical atomic bomb was tested. The bomb was dropped from an IL-28 jet aircraft at an altitude of 11 km and exploded at 600 m, with a yield of 28 kt. It was the first soviet mass-produced tactical nuclear weapon.
June 8, 1948, the Soviet Union launched its first reactor in Mayak, producing plutonium for nuclear weapons program.