Why didn’t U.S. Army commanders in Vietnam act on intelligence warning them that an attack was imminent? Over the years, I’ve concluded that there were multiple reasons.
First was that the National Security Agency (NSA), my employer, was very successful in keep the existence of signals intelligence a secret. Even the agency itself was so low profile that few people had ever heard of it. The employees never said that they worked for NSA. We worked for the Department of Defense. So many in the military had no knowledge of NSA or signals intelligence.
Second, U.S. Army training for its officers neglected schooling in what signals intelligence was, where it came from, or how to use it. All they knew was that they had a civilian (me) in their midst that was providing information about the enemy. Typical were the words of the commander of the U.S. 4th Infantry Division, Major General William Peers when he dismissed my warning about North Vietnamese forces preparing to attack at Dak To in 1967: “So I’m supposed to believe that some kind of magic allows a bunch of shaky girbs [acronym for GI rat-bastards], distinguished more for their spit than their polish and abetted by an unknown civilian, to use a tangle of antennas and funny talk to divine the combat plans of the enemy?”
Third, we Americans are famous for our can-do attitude. We tend to ignore negative indicators and stress the positive. The enemy offered no threat. How could a little fourth-class country like North Vietnam win a war against the greatest military nation in history?
And finally, the U.S. Army never understood how the North Vietnamese chose to fight the war. They stuck to guerrilla warfare as long as they were facing us. Their strategy was summed up in Mao Tse Tung’s words: “Enemy advances, we retreat. Enemy camps, we harass. Enemy tires, we attack. Enemy retreats, we pursue.”
I also worked with Marine Corps units throughout South Vietnam. Unlike the army, Marines listened carefully to what I had to say and exploited the intelligence I provided them. But the Marines were in the minority.
Hence the Cassandra Effect. I’m told that these days intelligence operatives and military commanders are so intertwined that the effect no longer cripples or leads to defeats. I pray that that is so.