Soviet-Era Secret Leakers Were Way Worse than Snowden Is Edward Snowden the "most costly leaker of American secrets in the history of the Republic," as Michael Hayden, former director of both the NSA and the CIA, claims? Not even close. In awarding Snowden the top spot, Hayden compares him not only to Bradley Manning, but to a number of Cold War spies. When it comes to actual damage to national security and quantity of secrets disclosed - and lives lost - so far the former Booz Allen employee isn't in the same league as America's most damaging spies. Edward Snowden's troubles pale in comparison to those of Ethel and Julius Rosenberg. Universal History Archive/Getty Images It isn't necessary to judge Snowden's motives or assess the morality of his actions to place the latter in historic context. While the public perceives leakers very differently from spies, the distinction is largely irrelevant to the damage assessors at the NSA's Fort Meade campus and throughout the U.S. intelligence establishment. In terms of acute damage to national security, William Weisband, a civilian contractor who worked in the 1940s for what would later become the NSA, is a serious contender for "most costly leaker" status. Like Snowden, Weisband worked at a relatively low-level job that gave him access to some of the nation's most closely guarded signals intelligence secrets. Weisband's disclosures were made covertly, in contrast to those of today's media-savvy leakers, and even after the FBI caught him, the NSA kept his treachery secret. Weisband's story eventually came to light as a result of the declassification of decrypted Soviet cables and the publication of detailed notes from the KGB archives smuggled out of Moscow by a former KGB officer, Alexander Vassiliev. It is described in Spies, a book Vassiliev wrote with American historians John Earl Haynes and Harvey Klehr. Weisband, a native Russian-speaker who was recruited by Soviet intelligence in 1934, was literally looking over the shoulder of an Army code breaker in 1946 as he deciphered a Soviet intelligence cable that provided the first glimpse of the depth of KGB penetration of political, military and industrial targets. Weisband witnessed the development of the crown jewel of American Cold War counterintelligence, the code-breaking program that came to be known as Venona. While Venona produced spectacular insights into Soviet espionage and led to the unmasking of scores of spies, it was based on the brilliant exploitation of a quirky flaw in Russian encryption practices. By the time the Army decoded the first Venona cable, the flaw had been corrected and KGB communications rendered impenetrable. Weisband's most damaging leak, however, involved less dramatic revelations. In early 1948, he informed the KGB that the Army Signal Security Agency (ASA) - which was later renamed NSA - had cracked Soviet military codes. By 1948 wartime friendship between the U.S. and USSR had curdled into military brinksmanship, so the revelation of this U.S. capability must have come as a terrible shock in Moscow. Much of the Soviet military technology, especially its radar, bore a strong resemblance to cutting-edge U.S. Army equipment. That was no accident. The Soviet response to Weisband's intelligence caused shock and consternation at ASA - over the course of a few months in 1948, the Soviet military upgraded all of its codes and ciphers. American intelligence's window into the Red Army's thoughts and actions was slammed shut. Weisband's actions created a deafening silence just as Stalin was contemplating the first communist military assault on American troops. If Weisband hadn't informed the Russians that their military communications were an open book, evidence of the massive transfer of materiel and military advisors from Soviet territory to North Korea might have persuaded President Truman and U.S. military leaders to act on intelligence warning of an imminent invasion. Clarification of the U.S. intention to defend South Korea might have deterred Stalin, who respected the threat of force. Certainly, if the invasion hadn't come as a complete surprise, South Korean forces wouldn't have been routed and many thousands of Korean and American lives would have been saved. The ability to read Soviet military communications during the conflict would have been invaluable. When American and allied forces poured into the Korean peninsula, they were surprised by the sophistication of some North Korean weapons systems which, as it turned out, owed much to the activities of a second espionage operation that produced innumerable and highly damaging leaks. Instead of pokey World War II-era planes, the communists deployed MIG fighters that were a match for the best American planes. American intelligence reports had predicted that it would take years for Soviet radar to catch up with equipment produced by the U.S. during World War II, but North Korean anti-aircraft batteries were guided by radar that was better than anything the U.S. had deployed against the Nazis. In fact, much of the Soviet military technology, especially its radar, bore a strong resemblance to cutting-edge equipment the U.S. Army hastily shipped to the Pacific. This was no accident. The KGB had for years been collecting vast amounts of technical information from American military contractors. Of the many Soviet espionage rings operating within U.S. industry, the most prolific was organized and operated by a fervent young communist named Julius Rosenberg. Debate about the value of the Rosenberg ring's atomic espionage has obscured the fact that it was one of the most effective military-industrial espionage operations in the history of spying. For example, Rosenberg gave the Soviets blueprints and a working copy of the proximity fuse, one of the United States military's most closely guarded secrets. Rosenberg and the engineers he recruited had unfettered access to specifications and manufacturing instructions for virtually every American radar system, the most advanced airplane technology, fire-control computers, and much more. One of Rosenberg's recruits, William Perl, gave the USSR 12,000-pages of blueprints for the P-80 Shooting Star, America's first jet fighter. Some Rosenberg apologists minimize the importance of the ring's activities by pointing out that the Soviet Union was a U.S. ally during World War II. But Julius and his comrades continued to pilfer American secrets for years after the defeat of fascism. Indeed, in 1948, Rosenberg, Perl and military contractor Morton Sobell copied thousands of pages of aviation secrets that Perl had "borrowed" from a safe at Columbia University. The haul was so large that Sobell staggered under the box of 35mm film canisters as he carried them to meet his KGB handler. Sobell and the other members of the Rosenberg ring were convinced at the time that war between the U.S. and USSR was inevitable, and they redoubled their efforts to collect information that could help the Soviet Union prevail. If he has a few hours to spare, Snowden might ask his handlers to drive him to Zelenograd, a city on the outskirts of Moscow that during the Cold War was the secret heart of Soviet computer R&D. In 1962, Alfred Sarant and Joel Barr, two members of the Rosenberg ring who had evaded the FBI and made it to safety behind the Iron Curtain, persuaded Khrushchev to build Zelenograd as the USSR's version of Silicon Valley. While most Cold War defectors to the USSR lived in drunken despondency, despised as traitors to their own country, Barr and Sarant were richly rewarded for their technical contributions to Soviet military industry - something for Snowden to think about if he remains in Russia.