Nuclear Weapons/Warheads: Russia

The groundwork for the Soviet atomic weapons program was laid in a series of papers on fission from 1939-1941 by Yakov Zeldovich and Yuli Khariton. The actual program did not begin until 1943.

Reports by Soviet intelligence revealed the rapid growth of the U.S. Manhattan Project, prompting Moscow to start its own atomic weapons program under the direction of physicist Igor Vasilievich Kurchatov. Sympathetic agents in the United States provided the Soviets with critical data,...