Ion Pacepa, former head of Romania's "KGB," claimed in his 2007 book,
Programmed to Kill: Lee Harvey Oswald, The Soviet KGB, and the Kennedy Assassination, that Oswald was trained or programmed in the USSR to kill JFK, and that after Oswald had returned to the U.S., Khruschev got "cold feet" but was unable to call the mission off.
As relayed to Richard Russell in
The Man Who Knew Too Much, someone whom Richard Case Nagell believed was CIA ordered him to talk Oswald out of unwittingly allowing himself to be patsied for the assassination by anti-Castro exiles posing as Castro's agents, and if that failed, to kill him. According to Russell, Nagell later determined that the ostensible CIA agent/officer was actually KGB.
Hmm
-- MWT
PS For those members and guests who dismiss out-of-hand the idea that Khrushchev would have wanted to kill JFK in the first place, I suggest that you read the chapter titled
Sinister Implications in Mark Riebling's 1994 book
Wedge: The Secret War Between the FBI and CIA.
https://archive.org/details/WedgeFromPearlHarborTo911HowTheSecretWarBetweenTheFBIAndCIAHasEndangeredNationalSecurity/page/n1