Toward the end of Last of the Annamese, the U.S. Ambassador dismisses intelligence indicating that the North Vietnamese will attack Saigon. That intelligence comes from the intercept and exploitation of North Vietnamese communications. The Ambassador claims, in a message to the U.S. President and Secretary of State, that the North Vietnamese have used communications deception to fool the U.S. signals intelligence specialists into believing that an attack is forthcoming. When Chuck Griffin, a retired Marine and intelligence officer working in Saigon, asks for the evidence to support such a conclusion, he is ignored.
Once again, the fiction follows fact. In March and April, 1975, I repeatedly warned the U.S. Ambassador, Graham Martin, that a North Vietnamese attack on Saigon was imminent. My signals intelligence data was rejected as successful North Vietnamese communications deception. The Ambassador forbade evacuation and even preparations for evacuation. I cheated and got 41 of my 43 subordinates and their wives and children out of the country before the end. Fortunately, General Homer Smith, the Defense Attaché, disobeyed the Ambassador and proceeded with evacuation planning in conjunction with the Department of Defense and Command-in-Chief, Pacific. The two communicators who volunteered to stay with me to the end went out by helicopter on the afternoon of 29 April. I went out that evening under fire.
To my knowledge, labelling signals intelligence data as communications deception has been rare in our history. I never knew of a case in which the label was accurate. Those of us who worked on North Vietnamese communications knew the target backwards and forward. Anything false transmitted for the purpose of fooling us would have been immediately obvious. That’s because communications deception is extremely difficult to design and carry out and it’s so easy to detect.
My memories of the Ambassador’s refusal to accept the intelligence warning of a forthcoming attack make me all the more uneasy about what’s going on right now with President Trump. He dismisses valid intelligence and blames the intelligence agencies for leaking. In my years in the business, it was rare if ever that a member of the intelligence community leaked classified information to the press. When leaks occurred, the source nearly always turned out to be an intelligence customer, that is, a recipient of the finished intelligence. The culprits, more often than not, were members of Congress or their staffs.