Maddox, two American ships on call in the Gulf of Tonkin. The first of these attacks occurred on August 2, 1964. A second attack was supposed to have taken place on August 4, although Vo Nguyen Giap, the DRV's leading military figure at the time, and Johnson's Secretary of Defense Robert S. McNamara have recently concluded that no second attack ever took place. In any event, the Johnson administration used the August 4 attack as political cover for a Congressional resolution that gave the president broad war powers. The resolution, now known as the Gulf of Tonkin Resolution, passed both the House and Senate with only two dissenting votes (Senators Morse of Oregon and Gruening of Alaska). The Resolution was followed by limited reprisal air attacks against the DRV.

Throughout the fall and into the winter of 1964, the Johnson administration debated the correct strategy in Vietnam. The Joint Chiefs of Staff wanted to expand the air war over the DRV quickly to help stabilize the new Saigon regime. The civilians in the Pentagon wanted to apply gradual pressure to the Communist Party with limited and selective bombings. Only Undersecretary of State George Ball dissented, claiming that Johnson's Vietnam policy was too provocative for its limited expected results. In early 1965, the NLF attacked two U.S. army installations in South Vietnam, and as a result, Johnson ordered the sustained bombing missions over the DRV that the Joint Chiefs of Staff had long advocated.

The bombing missions, known as OPERATION ROLLING THUNDER, caused the Communist Party to reassess its own war strategy. From 1960 through late 1964, the Party believed it could win a military victory in the south "in a relatively short period of time." With the new American military commitment, confirmed in March 1965 when Johnson sent the first combat troops to Vietnam, the Party moved to a protracted war strategy. The idea was to get the United States bogged down in a war that it could not win militarily and create unfavorable conditions for political victory. The Communist Party believed that it would prevail in a protracted war because the United States had no clearly defined objectives, and therefore, the country would eventually tire of the war and demand a negotiated settlement. While some naive and simple-minded critics have claimed that the Communist Party, and Vietnamese in general, did not have the same regard for life and therefore were willing to sustain more losses in a protracted war, the Party understood that it had an ideological commitment to victory from large segments of the Vietnamese population.