On 27 November 1965, the Pentagon declared that if the major operations needed to neutralize North Vietnamese and NLF forces were to succeed, U.S. troop levels in South Vietnam would have to be increased from 120,000 to 400,000. In a series of meetings between Westmoreland and the President held in Honolulu in February 1966, Westmoreland argued that the U.S. presence had succeeded in preventing the immediate defeat of the South Vietnamese government but that more troops would be necessary if systematic offensive operations were to be conducted. The issue then became in what manner American forces would be used.
The nature of the American military's strategic and tactical decisions made during this period would color the conduct and nature of the conflict for the duration of the American commitment. Classical military logic demanded that the U.S. attack the locus of PAVN/NLF in the North. If that country could not be invaded, then the enemy's logistical system in Laos and Cambodia should be cut by ground forces, isolating the southern battlefield. However, political considerations limited U.S. military actions, mainly because of the memory of communist reactions during the Korean War. Ever present in the minds of diplomats, military officers, and politicians was the possibility of a spiraling escalation of the conflict into a superpower confrontation and the possibility of a nuclear exchange. Therefore, there would be no invasion of North Vietnam, the "neutrality" of Laos and Cambodia would be respected, and Rolling Thunder would not resemble the bombing of Germany and Japan during the Second World War.