The USSR believed Lyndon B Johnson and an "ultra right-wing coup" was behind the assassination of John F Kennedy. Lyndon Johnson also happens to be friends to Prescott Bush, the father of George H.W. Bush, who married into the family line of George Herbert Walker. https://en.wikipedia.org/wiki/George_Herbert_Walker
Prescott Bush was also co-incidentally friends with Harry S. Truman who took over after Roosevelt happened to die all of a sudden. There was a regime coup attempt 12 years before that as well, the Business plot in 1933 against Roosevelt who had just taken office (that coup was stopped by General Smedley Butler. )
