As we approached their location, the enemy ceased communicating, a sign that they were on the move. I alerted the commander that the enemy was leaving its position. When we arrived at the target, the North Vietnamese units had faded into the jungle. We found plenty of indications that they had been there recently, but not a single enemy soldier remained. Obviously, they had been intercepting our communications and had fled, avoiding confronting a superior force as the North Vietnamese always did.
The U.S. commander I was supporting blamed faulty intelligence for our failure to find and engage the enemy. He asserted that signals intelligence was not reliable enough for targeting and, in effect, banned me from his presence.
The Cassandra Effect dogged me throughout the thirteen years I spent more time in Vietnam than I did in the U.S. At the end, it almost cost me my life. In April 1975, I repeatedly warned the U.S. ambassador to South Vietnam, Graham Martin, that signals intelligence provided overwhelming evidence that the North Vietnamese were preparing to attack Saigon. He refused to believe me and never called for an evacuation. By deception and outright lying, I was able to evacuate my 43 subordinates and their families, but I couldn’t leave. When the attack came, I escaped under fire.
I’m assured by those still active in government that things have changed. Nowadays, they tell me, government officials and military commanders are trained in the use of signals intelligence and exploit it regularly. For the sake of all working in the defense of the U.S., I pray they are right.
Tom Glenn, Writer 