Following are excerpts from Arthur M. Schlesinger Jr.’s Journals of 1966 and 1967.
January 21 
I have been meaning for some time to put down the substance of the evening of January 6 when I assembled Carl Kaysen, Dick Goodwin, and Ken Galbraith for a dinner at 3132 O Street with [Secretary of Defense] Bob McNamara.
The subject was, of course, Vietnam. Bob combined frankness about issues with discretion about personalities in his usual fashion. But it became evident that he was strongly in favor of the pause in the bombing of North Vietnam and had advocated it ever since he had felt the military equilibrium had been restored in the autumn. One gathered that the Joint Chiefs of Staff and [Secretary of State Dean] Rusk had opposed the idea, but that the President was eventually won over.
McNamara said, as he had before, that he did not regard a military solution as possible. The military advantages of the bombing, he seemed to feel, were marginal and were outweighed by the political disadvantages. The infiltration rate had increased steadily (fourfold?) since the bombing had started. He seemed skeptical about the value of enlarging our ground forces. At the 8:1 ratio, we could put in 80,000 men, the North Vietnamese could put in 10,000, and we would all be even again. He seemed deeply oppressed and concerned at the prospect of indefinite escalation. Our impression was that he feared the resumption of bombing might well put us on the slippery slide. When I asked whether the North Vietnamese had increased their commitment in response to or independently of American action, he said flatly the first.
He defined his objective in South Vietnam as “withdrawal with honor.” The establishment of a neutralist government in Saigon would meet that standard. When we asked whether there was a South Vietnamese Souvanna Phouma [the prime minister of Laos, who governed on a platform of national reconciliation], he said he thought there was: [Phan Huy] Quat. One gathered that he might even be prepared to consider Viet Cong participation in such a government—presumably on the Laos model (implying that the Viet Cong, like the Pathet Lao, would turn against a genuinely neutralist regime).
In times past, I have always thought that Bob lacked a political ear—that he had little instinct for the political and diplomatic dimensions of the problem. We were all deeply impressed by his apparent evolution. He obviously now has a clear and free grasp of the intangible factors in the Vietnam situation and is determined to prevent the conflict from billowing up into nuclear war with China. Evidently the secretary of defense and the secretary of state have exchanged roles—with McNamara asserting the political and diplomatic interests of the government and Rusk defending the views of the Joint Chiefs of Staff.
I have been meaning for some time to put down some notes about Vietnam. Things have got much worse since January. Probably …