When a reader found and read my blog of sometime ago about foreseeing the future, I went back and reread it myself. I realized that it needs updating.
Here’s the background: during the thirteen years when I spent more time in Vietnam than I did in the U.S., I became an expert on foretelling what the North Vietnamese were going to do based on signals intelligence—the intercept and exploitation of their radio communications. In the referenced post, I described letting my mind wander over the facts and suddenly knowing what the North Vietnamese would do next. While that description was accurate, it didn’t reveal what was really going on.
During my years in Vietnam, I was continuously observing the North Vietnamese in action. Fortunately for me, they were quite rigid in the way they went about their business. To wit, when they were preparing for combat, they invariably moved their combat units close to the target (movements which we could detect through airborne radio direction finding [ARDF]), established a forward command post to run the operation, set up a watch net (the control station was on the air twenty-four hours a day, ready to respond to subordinate calls), replaced their one-time pad ciphers with simplified codes (that we could break and read), and introduced a simplified signal plan (callsigns, schedules, and frequencies) for greater ease in communicating while on the move. The final tipoff came when the forward command post assumed communication control of the combat units. That told us they were ready to attack.
More in the new year.
Tom Glenn, Writer 