Dear Walter,
Hoover would have covered up for Castro and/or Khrushchev for three reasons:
1) Like any human being, he wouldn't want to die in a Mutually Assured Destruction-guaranteed nuclear Armeggedon with the USSR.
2) He would't want to be caught with "egg on his face" for not having prevented the assassination.
3) He didn't care for JFK very much, anyway.
D'oh
-- Mudd Wrassler Tommy 
Hoover would have covered up for Castro and/or Khrushchev for three reasons:
1) Like any human being, he wouldn't want to die in a Mutually Assured Destruction-guaranteed nuclear Armeggedon with the USSR.If you knew that you would die as a consequence of act of killing a criminal who was holding a hand grenade (insuring mutual destruction ) would you pull the trigger?
The vast majority would not....because self preservation is THE number one driving force in life.... Hoover like many of the war hawks in the Pentagon weren't afraid of the Russians... so he would NEVER have covered up for them...
2) He would't want to be caught with "egg on his face" for not having prevented the assassination.Agreed.....But he'd have been covered with egg if it was learned that he knew that LHO had loudly threatened the life of JFK and he had not had him arrested the instant he stepped on US soil....
3) He didn't care for JFK very much, anyway.I gotta hand it to ya, Mudd.... I don't believe that there's ever been a greater understatement posted in this group.....Can you say LOATH?.....