Of all cases of Cold War conflict in which the United States could have used nuclear weapons, the Vietnam War provides one of the strongest “tests” of a nuclear taboo. In Vietnam, the United States chose to lose a humiliating and destructive war against a small, non-nuclear adversary while all its nuclear weapons remained on the shelf. During the ten-year military commitment to South Vietnam in the 1960s and 1970s, the United States sustained large losses in men, money, and materiel at tremendous political cost. US officials repeatedly declared that the United States could not tolerate the loss of Southeast Asia to Communism, and that the war was vital for US interests, prestige, and security.

As the war escalated, the United States was willing to maintain policies of great destructiveness. Operation Rolling Thunder, begun in March 1965, continued for three years and dropped more bombs on Vietnam than were dropped on all of Europe in World War II. Starting in 1969, B-52 raids demolished vast areas in North and South Vietnam, Cambodia, and Laos. US forces employed herbicides and defoliants to obliterate croplands and forests, dropped flame throwers and napalm, and eventually mined Haiphong harbor. It is estimated that some 3.6 million Vietnamese in both North and South, were killed in the conflict, and 58,000 Americans.