SIGINT in Vietnam

Despite the fact that it was successfully kept secret for many years, SIGINT (signals intelligence—the intercept and exploitation of enemy radio communications) was a major player in the U.S.’s war against the North Vietnamese invaders, ending in 1975. All four services (army, navy, air force, and Marines) deployed large numbers of cryptologic specialists to Southeast Asia during the war. Their work was overseen and directed by my employer, the National Security Agency (NSA). I’m not at liberty to discuss the numerous successes of NSA and the service cryptologic agencies (SCAs)—they’re still classified—but there is considerable public information indicating that they were very effective.

The size and importance of the effort is suggested by the fact that the first and last servicemen killed in Vietnam were connected with the SIGINT effort. The first soldier killed there, on December 22, 1961, was army Specialist James T. Davis, a radio direction finding operator. The Viet Cong ambushed him on a road near Saigon.

The last two American service men killed on the ground in Vietnam were Marines who were guarding the DAO building where I was working. Not long before they died, I was out in the compound talking to them. I was head of the U.S. clandestine SIGINT operation in Vietnam. So those two Marines, named McMahon and Judge, were also closely connected to our intelligence effort.

More next time.

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