70% to avoid humiliation. Crazy.
The notion of credibility was huge during the Cold War. That is what is being referred to here through the goal of avoiding humiliation.
What is it to be credible? Robert McMahon says: “To be credible means that others will believe your threats and your promises and act accordingly.” [Source]
As so much of the Cold War relied upon rhetoric and the perceived meaning of actions, American leaders consistently cited credibility as a top foreign policy objective. In the specific context of Vietnam, upholding the promise to keep South Vietnam free of communism translated into allies and potential allies seeing the US as a strong protective power with prestige. For enemies, protecting South Vietnam also translated into strength and power as a deterrent.
If you can access it, definitely check out: “Credibility and World Power: Exploring the Psychological Dimension in Postwar American Diplomacy” by Robert J McMahon.