The U.S. National Security Agency waited almost 50 years before releasing the first batch of Soviet cables decrypted by the Venona project, most of which were broken between 1947 and 1952.

In December 1946, in one of the earliest Venona breakthroughs, Meredith Gardner, an analyst with the Signal Intelligence Service (an NSA forerunner), broke into a 1944 KGB message that gave a list of the leading scientists working on the Manhattan Project, the effort to build an atomic bomb.

Twenty-one deciphered KGB cables, all from 1944 and 1945, discuss Julius Rosenberg, who bore the covernames "Antenna" and, later, "Liberal."

Julius and Ethel Rosenberg, who were executed at New York's Sing Sing Prison on June 19, 1953, were the only persons put to death for espionage in the U.S. during the Cold War.

The Venona intercepts reveal that the Soviets never gave Ethel Rosenberg a cover name—evidence, say her sons Robert and Michael Meeropol, that she was innocent of espionage.

In a December 5th, 2001, Associated Press story, David Greenglass admitted he lied under oath about his sister Ethel's involvement in espionage to reduce his own sentence and keep his wife Ruth out of prison.

Nearly a half century after the death of his sister, David Greenglass and his wife Ruth are alive and well, living under assumed names in the New York area.

Ted Hall, another spy within the Manhattan Project, was a physics prodigy who attended Columbia University at age 14 and graduated from Harvard at age 18.

The KGB gave Hall the cover name "Youngster," because when he first passed secrets to the Soviets about the atomic bomb, he was only 19 years old.

Hall told his wife Joan that he gave the U.S.S.R. secrets of the atom bomb because he was afraid the U.S. might become a very reactionary power after World War II, and that the Soviet Union was the only country capable of standing up to it.

After the war, Hall earned a doctorate at the University of Chicago and eventually moved to England. Neither he nor his principal courier Saville Sax was ever prosecuted.

Till the day he died, on November 1, 1999 at the age of 74, Hall never fully admitted to undertaking espionage.

Klaus Fuchs, perhaps the most damaging spy within the Manhattan Project, made a full confession in 1950, served nine years in prison, and then moved to Communist East Germany, where he died in 1988.

Within months of Fuchs' confession, which led to several arrests, the spies Joel Barr and Alfred Sarant disappeared. Nothing more was heard from them until 1983, when a Harvard researcher identified them as the leading Soviet scientists Joseph Berg and Philip Georgievich Staros.

In the end, Venona was seriously compromised by the American William Weisband and the Englishman H.R. "Kim" Philby, both of whom had access to Venona apparently told the Soviets about the program.

Venona shows that the KGB's cover names for American concerns included "Enormoz" (the Manhattan Project), "Arsenal" (the U.S. War Department), and "The Bank" (the U.S. Department of State).

In a KGB message, a member of the American Communist Party was known as a "Fellowcountryman," while a member of the Young Communist League was called a "Gymnast."

To date, the NSA has declassified more than 3,000 messages related to Venona.

Yet of the voluminous message traffic sent to Moscow from the KGB's New York office, Venona cryptanalysts were able to decrypt only 49 percent of the 1944 messages, 15 percent of the 1943 messages, and a mere 1.8 percent of the 1942 messages.

Many persons known in the Venona traffic only by their cover names have never been identified, including "Quantum," a spy who gave valuable scientific information about the atom-bomb project to the Soviets at a meeting at the Soviet embassy on June 14, 1943.