4. The KGB Theory
Along with American government agencies being embroiled in conspiracy theories to kill the President, the Russians were also suspected of the covert assassination. This is a theory that is given weight by the fact Oswald had well-known ties with the USSR, regularly travelled there, had a Soviet wife and had reported frequent contact with Soviet diplomats. If the Cubans had a reason to despise Kennedy, so too did the Russians - the nationally embarrassing conclusion of the 1962 Cuban Missile Crisis being a prime example. One version of a KGB plot to kill Kennedy centres around Oswald being "programmed" to kill the leader and that he was brainwashed into doing so.