Since 1950, five American Presidents have supported a series of policies designed to maintain a pro-West, anticommunist government in control of South Vietnam. The persistence of such policies exhibits remarkable continuity, given the enormous difficulties encountered in pursuing this objective. There have been many efforts to explain the origins and durability of the American commitment. None has proved entirely satisfactory. It seems clear that the impetus for the policy arose from at least three principal objectives: the containment of the world communist movement, the more specific containment of mainland China, and the containment of revolutionary nationalism. But such goals can be pursued in a variety of ways, and it remains unclear why over the years the United States was prepared to make such immense sacrifices in blood, treasure, and prestige in their pursuit.

One rationale offered was the recollection that policies of appeasement – in what might be called the “lesson of Munich” – had not prevented World War II. American policy-makers prominent during the buildup of a military commitment to defend the Saigon regime seemed to believe the idea that the international communist movement was monolithic and committed to world conquest; they therefore saw the choice as one between “standing up to aggression” or provoking World War III. The notion of “containment” or “holding the line” arose as a reaction to Stalinism but persisted into the 1960s, long after Stalin's death and despite hard evidence of a deep Sino-Soviet split. This notion was accompanied by an image of “falling dominoes”: If South Vietnam should fall to communism, then Thailand, Cambodia, Laos, and the Malay peninsula would also fall in inevitable succession. Therefore, although the stakes in Vietnam might appear small and remote if taken in isolation, it was argued that a large commitment was nevertheless justified because of these larger concerns – namely, the geopolitical stability of all of South Asia and the establishment as precedent of a significant prohibition against a communist aggressor.

Such reasoning is abstract and ideological and does not fit too well with the concrete facts of conflict in Asia, especially in Vietnam. When the United States made its original economic commitment to the French in 1950, the struggle for Indochina was a typical anticolonial war of independence of the sort that developed in Asia and Africa after World War II.