One story about the army’s failure to exploit signals intelligence (SIGINT) stands out. In the middle years of the Vietnam war, I was working in the central section of the country near the coast in support of an army combat unit. U.S. SIGINT units were intercepting the radio communications of a major North Vietnamese unit and located it north of us using airborne radio direction finding (ARDF). The American unit’s commander decided to attack the communist unit. He set out with his forces for the unit’s location. But while he was en route, he continued to communicate with his subordinate units by radio. Worse, he was communicating in the clear, with no encipherment. I warned him repeatedly that only by radio silence could he take the enemy by surprise. He ignored me.
When we reached the enemy’s location, there were plenty of signs that they had been there, but they were gone. The commander’s continuous use of radio communications had tipped them off.
The commander blamed the mission failure on poor intelligence—he claimed that the ARDF locations I had supplied him were erroneous. After that, he refused to exploit the SIGINT I was able to provide him.
The Marine colonel who rescued me during the fall of Saigon, Al Gray, went on to become General Gray and eventually rose to be the Commandant of the Marine Corps. He was the finest leader I ever encountered, devoted to accomplishing his mission and looking out for the welfare of his subordinates. Now 93 years old, General Gray still responds to my email messages. I’ll be emailing him again on April 29, the forty-seventh anniversary of the fall of Saigon, when I escaped under fire. I survived thanks to Al Gray.
Tom Glenn, Writer 