How did Johnson kill Kennedy?
Well, Kennedy became a dove when the Cuban Missile Crisis almost ended human civilization. He became convinced that the U.S. needed to work out a peace and disarmament deal with the Soviet Union, and was communicating fruitfully with Soviet premier Nikita Kruschev on this matter. Check out JFK’s American University Speech, where JFK talks about the need for peace with the Soviet Union and a disarmament treaty only 5 months before his assassination.
At the same time, Kennedy became distrustful of the CIA and the military elite after the Bay of Pigs fiasco, and after the Joint Chiefs of Staff (the heads of the military) submitted an official proposal to him including suggestions to set off bombs in the U.S., killing civilians, to blame on Castro and thereby justify a war with Cuba in the public mind. This proposal was titled Operation Northwoods, and was vetoed by Kennedy.
Kennedy is on record as as asking '"How could I have been so stupid?" to trust the groups who were advising him, such as the CIA and the Joint Chiefs of Staff, and that he would “splinter the CIA into a thousand pieces and scatter it into the winds.”
Rather than be splintered and scattered, the CIA, or rather a faction of it, decided to have Kennedy shot, blaming it on a pro-Castro lone nut gunman, Lee Oswald. The people who actually killed Kennedy were most likely the members of Operation 40, a CIA squad of cold-war hardliners who were involved in attempts to kill Castro, and thus had the resources, training and motivation to carry out the assassination of a head of state, so that hard-line cold war policies would remain in place.
LBJ apparently was approached and went along with this plan, and, becoming President after JFK’s assasination, LBJ organized the Warren Commission to ‘investigate’ Kennedy’s death. The Warren Commission included the head of the CIA, Allen Dulles, future President Gerald Ford, and head of the World Bank, John J McCloy. Would you appoint a banker to investigate a murder?
Members of ‘Operation 40,’ like Barry Seal, later became involved in drug and arms running on behalf of right-wing CIA backed paramilitaries in South America. Others, like Frank Sturgis, were later arrested in the “Watergate burglaries.”
For further reading, you might want to check out the cases of William F. Pepper or research George H. W. Bush’s father’s attempt to overthrow the government of the United States in the so called 'business plot,’ and then in that light evaluate his son George’s later leadership of the CIA.
below; pictures of Frank Sturgis, Operation 40 member, Watergate burglar; in the middle one, Sturgis is dressed as a “tramp,” the outfit he was wearing when was arrested by Dallas police for being suspicious in the immediate aftermath of the Kennedy assassination: