Document of Robert McNamara's memo of july 20, 1965 recommended the escalation in Vietnam:
Options open to us. We must choose three course of action with respect to Vietnam all of which involve different probabilities, outcomes and costs:
( a ) Cut our losses and withdraw under the best condition that can be arranged-almiost certainly conditions humiliating the United States and very damaging to our future effectiveness on the world scene.

( b ) Continue at about the present level, with the US forces limited to say 75,000 holding on and playing for the breaks - a course of action which, because our position would grow weaker, almost certainly would confront us later with choices between withdraw and an emergency expansion of forces, perhaps too late to do any good.

( c )Expand promptly and substantially the US military pressure against the Viet Congs in the south and maintain military pressure on the north Vietnamese in the north while launching vigorous effort on the political side to lay the ground work for a favorable outcome by clarifying our objectives and establish channels of communication. this alternative would stave off defeat in the short run and offer a good chance producing a favorable settlement in the longer run; at the same time it would imply a commitment to see a fighting war clear through at considerable cost and casualties and material and would make any later decision to withdraw even more difficult and even more costly than would be the case today.
My recommendation in paragraph 5 below are base on the choices of the third alternative ( option C [in this passage] ) as the course of action involving the best odds of the best outcome with the most acceptable cost to the United States.


Document from the Lyndon Baines Johnson Library.