Executive Action is a Burt Lancaster movie from 1973 which tells a fictional account of how and why the assasination of President Kennedy was carried out.
Using real footage from the era, the movie tells, in a cold, almost documentary style, how a group of ultra-rightwing industrialists initiates, debates and plans the murder.
Although lacking the charm of The Day of The Jackal, it does a very believable and workmanlike job of identifying how the assasination was carried out and then covered up with Lee Harvey Oswald as a prepared patsy.
It was actually quite ironic that Lancaster plays one of the chief conspirators given that he had been a life long liberal, even campaigning, at the end of his career, for Michael Dukakis in 1988.
Not yet released in English primarily for region 2, it is available on region 1, and worth a watch, especially for its curiously mournful soundtrack and the chilling “real power in America” opening montage. It has been posted on Youtube at various times.