We need a new conspiracy theory! And I have one!
Israel whacked Jack because he knew too much about Dimona!
No, seriously, within the warped thinking of conspiracy theorists, this one is totally sane. Per the National Security Archive website, Jack warned Israeli Prime Minister David Ben-Gurion in 1963 that failure to be able to inspect Dimona would jeopardize US-Israel relations. Seriously:
Beginning in April 1963, Kennedy insisted that the Israeli leadership accept regular bi-annual U.S. inspections, or in diplomatic language, “visits,” of Israel’s nuclear complex at Dimona in the Negev Desert. Prime Minister David Ben-Gurion and his successor, Levi Eshkol, tried to evade and avoid inspections, but Kennedy applied unprecedented pressure, informing them bluntly, in a near ultimatum tone, that Washington’s “commitment to and support of Israel “could be “seriously jeopardized” if it was thought that the U.S. government could not obtain “reliable information” on the Dimona reactor and Israel’s nuclear intentions.
And, per that piece, Ben-Gurion and his successor, Levi Eshkol, did all they could to stall Jack out.
And, the timing fits:
In early 1963 American concerns resurfaced. In January, Kennedy received a new National Intelligence Estimate (NIE) that highlighted the weapons potential of Dimona. It pointed out that the Dimona complex was likely to be operational later that year. According to the NIE, once Dimona was operating at full power, Israel might be on its way to produce enough plutonium for one or two weapons a year.
Boy, oh boy.
Ben-Gurion was expected to respond to Kennedy’s request on Dimona during his next meeting with Barbour, but he was not ready for a direct showdown with a determined U.S. president. Nor was he ready to accept Kennedy’s goal of semi-annual visits; that would have ended Dimona as the embodiment of Ben-Gurion’s existential insurance policy. Instead, he tried to avoid a confrontation by diverting Kennedy’s attention.
"Diverting" Kennedy, eh? What's the ultimate diversion?
But, it would have been Eshkol to have done that, as Ben-Gurion soon resigned. But Kennedy wouldn't let him off the hook.
Surprised by Kennedy’s tough demands on Dimona just days after taking office, Eshkol’s first response was to ask for more time for consultations. Only on 19 August, more than six weeks after he received the letter, did Eshkol come up with a response, which at times was vague. Under Kennedy’s pressure, Eshkol reluctantly assented, in principle, to allow regular visits by U.S. scientists to Dimona. Nevertheless, he did not agree to an early visit and avoided making a commitment to the bi-annual U.S. inspections that Kennedy sought.
Aug. 19, eh? Tight frame, but three months for an organization as skilled as Mossad, which had pulled off the Adolf Eichmann kidnapping just three years earlier? Not a problem.
Since Mossad had nabbed Khrushchev's famous de-Stalinization speech, it likely had eyes on Lee Harvey Oswald when he went to the USSR, and again when he came back to the US. Oswald's attempt to infiltrate the DRE would have been seized on as the opportunity to use him.
Mossad agents would have been able to play up Oswald's leftist sympathies and brainwash him. He would be disposable as an assassin and untied to them. In case he were arrested, Jack Ruby, being Jewish, would be a perfect "cut-out" to take out Oswald. After all, he admitted to Earl Warren himself during Warren Commission investigation that he was being controlled:
Ruby could well have been paying off an IOU the day he was used to kill Lee Harvey Oswald. Remember: "I have been used for a purpose," the way Ruby expressed it to Chief Justice Warren in their June 7, 1964 session.
There you go. Not the mob, but Mossad, was the Shin Bet, not Cosa Nostra, to whom he owed a debt.
Finally, this explains everything LBJ.
He knew early on the Mossad background, because he got hints sent to him. The Warren Commission was created as a cover-up. And, with those "hints," this is why he never pushed Israel on Dimona the same way Jack did. And I haven't even mentioned the USS Liberty.