I'm sorry, Joe, but JFK did not wish for the Diem assassination.
Rather, he wired his Ambassador to Viet Nam, the newly appointed Henry Cabot Lodge (an attempt at reaching across the aisle, as Lodge actually ran against him as Nixon's VP), "We wish to give Diem REASONABLE opportunity to remove Nhus (Ngo Dinh Nhu and Madame Nhu), but if he remains obdurate, then we are prepared to accept the obvious implication that we can no longer support Diem."
Lodge took this as an opportunity to consult with longtime CIA ally Henry Luce, rather than his President, as to his course of action.
Lodge soon decided not to give Diem "reasonable opportunity"
In short order President Kennedy's wishes were undermined by Lodge.
He was informed by Michael Forrestal, that Acting Sec of State James Ball, Averill Harriman, ( yes, of THAT Harriman family), and Roger Hilsman had backed Lodge's decision to undermine the President's directive and give Diem no opportunity, at all, to forestall a coup.
Kennedy was furious that his decision making had been usurped and manipulated.
To Forrestal, who offered to resign for his role in short circuiting the process, Kennedy told him "You're not worth firing! You owe me something, so you stick around!"
Further attempts to reach and instruct Lodge, through Dean Rusk, were evaded.
LBJ's decision to reverse the direction of JFK's plan to leave Viet Nam, lock, stock and barrel, by 1965, was, as Jim Garrison later pointed out, made within hours of President Kennedy's murder, WITHOUT SO MUCH as a Position Paper or Fact Finding Mission to justify it.
This info, footnoted and corroborated, and much, much more, is readily available in James W. Douglass's 2008 work of Historical Non Fiction "JFK and the Unspeakable - Why He Died and Why It Matters"
It should be required reading in all Public Schools.