The core component of the credibility imperative was an assumption that a failure to stand firm in the war would cause allies around the world to question, and perhaps lose faith in, America’s commitment to their defense, and would embolden adversaries to act aggressively. It was a kind of “psychological domino theory,” as Jonathan Schell has put it, and there was but one thing wrong with it: it did not reflect the realities of the international system of late 1964-early 1965.6
