The Venona Project: Decoding Soviet Spies

The Venona project was a top-secret American-British intelligence effort that decrypted Soviet communications from 1943-1980. The project revealed that the Soviets had deeply penetrated the Manhattan Project, the U.S. Treasury, the State Department, and the OSS (precursor to the CIA). Over 3,000 messages were decoded, identifying hundreds of Soviet agents, including Julius Rosenberg, Alger Hiss, and even a spy inside the British embassy in Washington. Most of the identified agents were never prosecuted because the information couldn't be revealed in court.