Rob,
Why should I make things super-easy for you by trying to paraphrase, in fifty-words-or-less, what Mark Riebling and true-defector Pyotr Deryabin (ever heard of him?) say were excellent reasons for Nikita Krushchev's assassinating President Kennedy (with or without the help of Fidel Castro)?
Click on the link I provided, read the book (or at least the one page I pointed out to you), and then try to rebut what Riebling says.
It'll be good for you, and you might even learn something!
Or, if you prefer, avoid that information and that "take," and continue right along in ... well, ignorance ..., and continue to unwittingly spread the injurious products of "KGB" "active measures" and "operational deception" ops.
(You'll have to read Bagley's book "Spy Wars" (for free on the Internet) if you want to understand what those two forms of Russian counterintelligence operations are all about, and how the former has been so effective against our country and our allies for eighty-plus years, and especially after it was augmented -- by a kind of feedback system -- by the latter in 1959.)
-- Tommy
PS As to just two of the things the Kremlin got out of "it", I give you fifty years of dumbing-down and paranoia-inducing Tinfoil Hat Conspiracy Theories ("scoops" and "intel" gleefully provided over the years by the Ruskies; mostly revolving around the evil, evil, evil CIA, of course; on all SORTS of subjects), and the concomitant eventual installing of Russian Mobbed-Up "useful idiot" Donald Trump as our president by "former" KGB Counterintelligence officer Vladimir Putin, and his lackey-agent, Julian Assange.