De Gaulle thought Kennedy was killed by his own security forces
He said Lee Harvey Oswald was a chosen front, and that America would keep silent to preserve order.

Who Killed JFK? · 48 Hours AfterIn the days after President John F. Kennedy was shot in Dallas, French President Charles de Gaulle gave his own verdict in private. He shared it with his information minister, Roger Parafit, who later recounted it in a memoir.
De Gaulle told Parafit, in the account, "What happened to Kennedy is what nearly happened to me." He meant, he said, "The security forces were in cahoots with. With extremists."
Asked whether Lee Harvey Oswald was a front, de Gaulle answered that everything led him to believe it. Describing Oswald, de Gaulle said, "He had a subpar intellect and was an exalted fanatic. Just the man they needed, the perfect one to be accused." When Oswald ran, de Gaulle said, it was probably because he had grown suspicious, and his handlers wanted him killed on the spot before the courts could take him.
That, de Gaulle argued, was how security forces everywhere handled such plots. De Gaulle continued, "security forces all over the world are the same when they do this kind of dirty work. As soon as they succeed in wiping out the false assassin, they declare that the justice system no longer need be concerned, that no further public action was needed now that the guilty perpetrator was dead."
Then came his most chilling line, de Gaulle said: "Better to assassinate an innocent man than to let a civil war break out. Better an injustice than disorder." America was in danger of upheaval, he believed, and Americans would close ranks and observe a law of silence.
They would do everything to stifle scandal, he predicted, so as not to lose face before the world, so as not to risk riots, so as to preserve the union and avoid a new civil war. As he put it, they would not ask questions they did not want answered. "They won't allow themselves to find out."
Questions people ask
What did de Gaulle mean by what nearly happened to him?
Yes. De Gaulle survived several assassination plots during his presidency, most famously an ambush in 1962 at Petit-Clamart outside Paris, when gunmen fired on his car. He often said French security and military factions were entangled with the extremists trying to kill him over Algerian independence.
Why would killing Oswald stop an investigation?
De Gaulle argued that a dead suspect gives officials a way to close the case. Once authorities can say the guilty man is dead, he said, they can claim no further prosecution is needed and pressure for a wider inquiry fades. That was his explanation for why Oswald's own killing mattered so much.
Why did he think America faced civil war?
De Gaulle believed America was fragile and deeply divided in the early 1960s, and that admitting a plot inside the government could shatter public trust. In his view, leaders would choose a painful but contained injustice, blaming one dead man, over disorder or mob violence. Preserving national unity, he said, would matter more than finding every answer.