Of the many battles the U.S. fought in the Vietnam War none hurt more than the 1965 battle in the Ia Drang Valley and the 1968 Tet Offensive. The outcome of those clashes and hundreds of smaller ones were not the clearcut, decisive victories that senior American commanders expected. That’s because they didn’t think the “primitive” enemy was shrewd enough and sophisticated enough to intercept radio communications, then use that information against U.S. troops. When it was conclusively proved that the North Vietnamese Army and Viet Cong had those capabilities, military intelligence agencies briefed Gen. Creighton Abrams, the head of Military Assistance Command, Vietnam, in early 1970. He responded: “This is terrible. They are reading our mail, and it has to stop! Get the word out to every division and corps commander.”
The enemy radio intercepts shouldn’t have been a surprise. There had been warning signals for years. In the late 1950s the Army directed its Electronics Command at Fort Monmouth, New Jersey, to develop a new “family” of single-channel tactical field radios to replace the obsolete inventory of World War II and Korean War field radio equipment still in use. At the same time the Defense Department directed the National Security Agency to concurrently develop and field “communications security equipment,” to encrypt all tactical voice and data radio equipment developed by the services.
The result was a series of Army and joint services security regulations and directives incorporated into the equipment specifications for new Army single-channel combat network radios. The Army built a mostly transistorized vehicular
