When American military personnel arrived in Vietnam during September of 1965, they could not have known about earlier Johnson Administration debates. What was the dilemma? How the war (if any) should be fought. What was the nature of the discussions? Let’s take a look.
People like McGeorge Bundy and Robert McNamara (who knew little about Vietnamese history and the North and South conflict), recommended action that had drastic consequences. Their legitimate concern was “containing” Communism, but their knowledge base was incomplete. They even failed to learn from the French experience in Vietnam, which ended disastrously in 1954.
The Administration’s well-founded fear was that China and the Soviet Union would support the North if America did too much to support the South. But if one makes a decision to "do something," the plan must be "to win" and the effort must be "all-out." Such, unfortunately for America’s dead and wounded, was not the case in Vietnam.
He [President Johnson] and his aides, poised to escalate the war, awaited the pretext to strike. It was, McGeorge Bundy said, like waiting for a "streetcar." (Page 411)
The "pretext to strike" occurred with the Camp Holloway attack. Bundy was in South Vietnam when that happened. Aleksei Kosygin (the new Soviet prime minister) was coincidentally in Hanoi. Karnow, quoting from a Bundy memo to the President, continues (at page 411):
In pressing the president to make a decision, Taylor [General Maxwell Taylor, then Ambassador to South Vietnam] had recommended that Mac Bundy visit Vietnam to appraise the situation. Bundy had never been there and was "physically detached from the local scene," and he might assure Johnson that "we are missing no real bets in the political field." So Bundy scheduled a trip for the beginning of February, 1965. But he was scarcely going with an open mind.