Historians believe that at least six scientists devising America's first nuclear weapons in the 1940s spied for the Soviet Union. In 1944-45, Fuchs and Hall gave Soviet intelligence agents detailed information about nuclear implosion research at the Los Alamos lab that led directly to the development of the first Soviet hydrogen bomb. In 1950, British authorities arrested Fuchs, then working for the U.K. Atomic Energy Authority. He served nine years in prison, then was released to East Germany, where he became a lecturer in physics. He was never arrested.
Some experts say that the benefits of openness outweigh the risks.
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