Atom Spies

"Atomic spies" or "atom spies" were people in the United States, Great Britain, and Canada who are known to have illicitly given information about nuclear weapons production or design to the Soviet Union during World War II and the early Cold War. Exactly what was given, and whether everyone on the list gave it are still matters of some scholarly dispute, and in some cases, what were originally seen as strong testimonies or confessions were admitted as fabricated in later years. Their work constitutes the most publicly well-known and well-documented case of nuclear espionage in the history of nuclear weapons. There was a movement among nuclear scientists to share the information with the world scientific community, but it was firmly quashed by the U.S. government.

Confirmation about espionage work came from the Venona project, which intercepted and decrypted Soviet intelligence reports sent during and after World War II. They provided clues to the identity of several spies at Los Alamos and elsewhere, some of whom have never been identified. Some of this information was available but not usable in court for secrecy reasons during the 1950s trials. Additionally, records from Soviet archives, which were briefly opened to researchers after the fall of the Soviet Union, included more information about some spies.

Before World War II, the theoretical possibility of nuclear fission occasioned intense discussion among leading physicists world-wide. Scientists from the Soviet Union were later recognized for their contributions to the understanding of a nuclear reality, and won several Nobel Prizes. Soviet scientists such as Igor Kurchatov, L. D. Landau, and Kirill Sinelnikov helped establish the idea of, and prove the existence of, a splittable atom. Dwarfed by and lost in the scale of the Manhattan Project, the significance of the Soviet contributions is rarely understood or credited outside of the field of physics. According to several sources, it was understood on a theoretical level that the atom provided for extremely powerful and novel releases of energy, and could possibly be utilized in the future for military purposes. In recorded comments, the physicists themselves lamented over their inability to achieve any kind of practical application from the discoveries. This would show that the scientists thought the creation of an atomic weapon was a pipe-dream and untenable. According to a US Congressional joint committee, although the scientists could conceivably have been first to generate a man-made fission reaction, in reality they lacked the ambition, funding, engineering capability, leadership, and ultimately, the capability to do so. The undertaking would be of an unimaginable scale, and the resources required to engineer for such use as a nuclear bomb, and nuclear power were deemed too great to pursue.

...
Wikipedia