The National Security Agency released declassified copies of VENONA messages. All of the released documents are available for review at the Museum Library and some significant messages are part of museum displays. 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 code named 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.