By the 1960s the salient features of American foreign policy were the domino theory, the Munich analogy, and the notion of a monolithic communist threat. American strategists believed that, in a world characterized by a life-and-death struggle between the forces of totalitarian communism and democratic capitalism, the fall of one nation to communism would inevitably lead to the fall of its neighbors. Moreover, to acquiesce in appeasement would only lead to further appeasement. Thus did the administrations of Democrats John F. Kennedy and Lyndon B. Johnson and the Republican administration of Richard M. Nixon feel it necessary to involve America in the burgeoning conflict between communist North Vietnam and noncommunist South Vietnam. At first there was strong bipartisan support for making Vietnam a testing ground for America's will to combat communism. In August 1964, after reports that North Vietnamese torpedo boats had attacked U.S. destroyers on the high seas in the Gulf of Tonkin, the Johnson administration secured Senate passage (with only two dissenting votes) of the Tonkin Gulf Resolution. In it Congress empowered the president to "take all necessary measures to repel any armed attacks against the forces of the United States and to prevent further aggression." The State Department subsequently called the resolution "the functional equivalent of a declaration of war." President Johnson did not reveal at the time that the U.S. vessels had been engaged in secret espionage and raiding activities directed against North Vietnam.
As the war progressed, opposition to it mounted in Congress. The activist foreign policies of the post–World War II era that produced the war in Southeast Asia were a product of the melding of conservative anticommunists who defined national security in terms of bases and alliances and who were basically xenophobic (many of them former Republican neo-isolationists), and liberal reformers who were determined to safeguard the national interest by exporting democracy and facilitating overseas economic prosperity. By 1966 a coalition of moderate-to-liberal senators, led by the powerful chairman of the Senate Foreign Relations Committee, J. William Fulbright, began to express doubts not only about the war in Vietnam but about the assumptions that underlay it. To them, nationalism was more important than the Cold War in precipitating Third World conflicts. The communist world, especially given the emerging Sino-Soviet split, seemed hardly monolithic. In addition, there was no convincing proof that if South Vietnam fell under the rule of communists, Thailand, Indonesia, and the Philippines would follow. Finally, and most important, congressional dissidents pointed out that most of the regimes the United States was defending in the name of democracy, including the governments of South Vietnam, were either authoritarian or totalitarian.
Lyndon Johnson had doubts about the war in Southeast Asia, but in order to get his domestic Great Society programs through Congress he perceived that he would have to appease the so-called conservative coalition—Southern Democrats and Republicans who had allied to battle the growth of the welfare state and federally mandated civil rights since the late 1940s—who were ardent in their anticommunism and hence supported the war in Vietnam. Johnson was obsessed with consensus and not just because of his desire to achieve domestic reform. He truly believed in the efficacy of bipartisanship in foreign policymaking. The contradictions inherent in the Cold War proved too much for the Texan, however. In 1968, facing opposition from the liberal and moderate wings of his own party, Johnson opted not to run for reelection, paving the way for the presidency of Republican Richard Nixon.
Nixon and his national security adviser and secretary of state, Henry Kissinger, were determined to create a new international order that would simultaneously contain communism and restore America's freedom of action. The new president could use his strong anticommunist credentials as a cover to build bridges to the communist superpowers. Once disarmed, the Soviet Union and Communist China could be persuaded to take their places as responsible members of the international community. Then, the great powers could act to control revolutions that threatened international stability. Unfortunately, such a policy was profoundly insensitive to the social and economic injustice and intense nationalism that characterized most Third World societies and that fueled the revolutions that the U.S. government hoped to contain. Although he quickly became disillusioned with Nixon, primarily because of the continuation of the war in Vietnam, Senator Fulbright was enamored of Henry Kissinger and his vision of a peaceful world based on rationality and a concert of interests. The administration's openings to China and Russia and its efforts to negotiate an end to the war in Vietnam generally enjoyed Democratic support—sometimes more so than from conservative Republicans.
Nixon had promised "peace with honor" in Vietnam. The president had no intention of surrendering South Vietnam to the communists; he merely wanted to turn the ground war over to the army of the Republic of Vietnam while continuing to furnish all-out military aid and to bomb communist positions throughout Southeast Asia. Congress, especially the Senate, had different ideas. A bipartisan coalition spearheaded by Fulbright and Republicans John Sherman Cooper of Kentucky and Jacob Javits of New York moved to limit the executive branch's power to make war. That effort culminated in passage of the War Powers Act by Congress in the fall of 1973 over President Nixon's veto. The measure obligated the president to inform Congress within forty-eight hours of the deployment of U.S. military forces abroad and bound him to withdraw them in sixty days in the absence of explicit congressional endorsement. The following week the House and Senate endorsed an amendment to the Military Procurement Authorization Act banning the funding of any U.S. military action in any part of Indochina.
America's ignominious withdrawal from Vietnam and the Watergate scandal created a crisis of confidence in national politics unknown since the Great Depression. The war in Vietnam brought home to Americans the truth that there were severe limitations to their nation's ability to determine the course of global events. Not only did it appear that the forces of international communism had scored a clear victory, but also that in the process of defending its perceived interests, the United States had transgressed many of the values and principles for which it claimed to be fighting. Moreover, Americans' sense that they had been lied to and deliberately deceived during crucial periods in the Vietnam War created an attitude of deep cynicism toward government at all levels, particularly the federal government.