NSA posts declassified intelligence from Korean War

The National Security Agency has setup a World Wide Web site where it plans to post newly declassified documents outlining the triumphs and pitfalls of signals intelligence — known as SIGINT - during the Korean War.

"In the coming weeks and months you can expect to see releases of newly declassified materials relating to SIGINT operations in Korea during 1950 [and] published articles detailing intelligence-gathering activities," said NSA's director, Air Force Lt. Gen Michael Hayden, in an introduction to the Web site.

The site represents NSA's latest effort to defrost itself from a Cold War footing and increase its public communication and education initiatives about the agency's contributions to national security.

The National Security Archive program at George Washington University has published an electronic briefing book, "The National Security Agency Declassified," which includes declassified documents relating to the history, organization and operations of the NSA, including the controversial global surveillance system known as Echelon.

The Web site's first installment outlines the signals intelligence contributions made before and during the war by the Armed Forces Security Agency (AFSA), the forerunner of NSA. The document discloses for the first time the details of an espionage case known to NSA officials as "Black Friday" and the resultant failure of NSA analysts to uncover evidence of a North Korean invasion of South Korea in 1950.

In 1934, the Soviet Union's intelligence service, the KGB, recruited William Weisband, a Russian linguist who had been working for AFSA. The KGB convinced him to divulge details of U.S. penetration of Soviet cipher systems. Then, two years before the start of the Korean War, "in rapid succession, every one of these cipher systems went dark," according to the NSA document.

Thanks to Weisband, the Soviets had conducted a massive change of all cryptological systems, denying U.S. intelligence critical communications intercepts. "This was perhaps the most significant intelligence loss in U.S. history," states the NSA document.

However, AFSA did score some successes. Although communications intelligence during the Korean War was "hampered by supply shortages, outmoded gear and equipment ill-suited to frequent movement over rough terrain," AFSA inadvertently discovered a new communications intercept tool. It soon became apparent that sound detection devices planted near enemy bunkers were capable of intercepting telephone calls. Known as "ground-return intercept," the new capability enabled collection of Chinese and Korean telephone traffic.