For all but the most determined denialists, that Julius Rosenberg was a Soviet spy was proved conclusively by VENONA — the ace in the hole for the Feds that they possessed in 1953 but could not show to the jury at the Rosenbergs’ trial, because it was so highly classified. Julius was every bit the traitor that the government said he was, and he had betrayed nuclear secrets to Stalin.

Contrary to assertions by Mr. Dukakis and sympathetic newspaper editorials, recently declassified archival evidence leaves no doubt that Ethel Rosenberg knowingly and eagerly abetted her husband’s espionage...

  The Venona decryptions, which were declassified by the National Security Agency and Central Intelligence Agency in 1995, showed that Soviet intelligence officers regarded both Julius and Ethel Rosenberg as valuable assets. Julius was the leader of a Soviet spy ring, and Ethel actively and knowingly assisted him.

   -Mark Kramer

Although the Rosenbergs had defenders who pleaded that they were innocent, or at least severely misunderstood, most of them fell silent when the National Security Agency twenty years ago declassified its VENONA project, a top secret code-breaking effort that revealed numerous 1940’s secrets of Soviet espionage against the United States.

  The unveiling of VENONA, one of the great triumphs of American intelligence, also revealed why Federal prosecutors were so confident in their prosecution of especially Julius Rosenberg. VENONA transcripts made clear that Julius, who appeared in the messages under the Soviet covernames LIBERAL and ANTENNA, wasn’t just a Stalinist true-believer but an important agent of the Soviet secret police who gave Moscow every American secret he could get his hands on. -The XX Committee