The JFK issue is somewhat like Lincoln. In Lincoln's case we learn that JW Booth did it.. but (as I recall) Eight people were tried and convicted for the crime and hung, I think.
I think sitting in Johnson's Library is a draft of the document Johnson signed reversing Kennedy's that called for the withdrawing of 'advisors' from VN. I forget the numbers atm... I do recall #11111 though which is another issue... The point is that it is dated November 21, 1963. Now this I've not confirmed directly but rely on Jim Marrs statement that he has a copy in his files..
A few comments on the JFK and Vietnam issue.
- JFK was one of our most, if not out most, pro-peace president in history - albeit one who was supportive a very large/powerful military as part of his approach.
(My editorial: I'm not sure he appreciated the danger of the huge military in the hands of some others, but he was fighting a cold war with nuclear war at stake).
- JFK was bombarded by military, and even his own staff, pushing for war in Vietnam. He held them off.
- JFK liked to delay choices, and he did so with Vietnam. He could go to war or not. He had not committed himself either way.
- JFK was preparing for the war option in case it was his choice IMO.
- Most people I think knew JFK best thought he was unlikely to have gone to war. His own Secretary of Defense who was the leading figure and if anything would have a bias to say JFK would have gone to war, Robert McNamara, said later he thought JFK probably would not have. JFK's friend Senate Majority Leader Mike Mansfield, William Manchester wrote, was sent on a trip to Vietnam for better feedback than he was getting from official channels - state and pentagon - and Mansfield told him he had to get out, and JFK told him that he planned to do so, but after the 1964 election. The best books on the topic, analyzing the available information, conclude JFK was unlikely to have gone to war.
- But while JFK's resistance to war in Vietnam was well known by the Pentagon and CIA, his plans to do so later were not known one way or the other.
- The NSAM's paint a slight picture of JFK laying the groundwork for Vietnam withdrawal, and he did remove 1,000 of the 16,000 advisors in October, 1963 as a symbolic gesture/message (whether it was more for the American people or the Diem regime isn't quite clear), but it wasn't a black and white 'LBJ overturned the plan to withdraw'.
- LBJ was more hawkish on Vietname than JFK, but even he saw it as a quagmire he had no idea how the US would get out of - before he went in. He'd gone over on another trip for JFK and gotten very close to Diem, as I said before calling him "the Winston Churchill of Southeast Asia" and my impression is he was furious when the US dropped support and he was assassinated.
IMO, Vietnam was not the strongest motive for the assassination - other than as part of the radical right-wing element who had it on a long list against JFK.
You can imagine a group of intelligence people, in the business of assassination, who saw JFK as someone who was betraying the US seeking peace with the USSR, refused to follow through on the Bay of Pigs, was a reckless drug-taking sex addict in the White House out of control and a menace to the interests of the nation - even as he again and again did not support our traditional right-wing dictators, such as his dropping of support for some European allies' colonial policies. They watched as Kennedy stopped US nuclear missile atmospheric testing, for example, and as he ordered an end to the assassination attempts against Castro. Motive? sure.