In February 1943, the U.S. Army's Signal Intelligence Service, a forerunner of the National Security Agency, began a small, very secret program, which was eventually codenamed VENONA. The object of the VENONA program was to examine, and possibly exploit, encrypted Soviet diplomatic communications. Analysis of the messages revealed that some of the messages were from KGB and GRU operatives working undercover in the United States.
In the summer of 1946, linguists began to read portions of the decrypted messages. Over the next several months, analysts uncovered references to the Manhattan Project and other espionage activities in the intercepted messages. U.S. Army Intelligence, G-2, became very alarmed at the content of the messages that were being decrypted and contacted the Federal Bureau of Investigation about the messages. The FBI used this information to develop leads that led to some arrests and convictions for espionage against the United States.
Eventually more than 2,000 messages were decrypted at least in part and showed the detail of KGB tradecraft, espionage against the U.S. Atomic Program, the large number of people (about 200) claimed as intelligence assets, and the activities of the American Communist Party among other things.
The National Security Agency has now released declassified copies of the VENONA messages. All of the released documents are available for review at the Museum Library and some significant messages are part of museum displays.
VENONA and the Rosenbergs
This display includes photographs of some of the American citizens who gave information to the Soviet KGB, replicas of the messages revealing the espionage, and some World War II-era artifacts similar to those used by KGB officers.
The Rosenbergs became a controversial case, due in part to the accusation and conviction of Ethel Rosenberg. VENONA messages indicate that her husband, Julius, was heavily involved in providing information to his KGB handler. At least one message shows that Ethel may have known about her husband's activities. Ethel's brother, David Greenglass, was also involved, selling details about the atomic bomb project in Los Alamos where he worked. It was David's testimony against his sister and brother-in-law that led to the conviction of the Rosenbergs for conspiracy to commit espionage.