Unfortunately, that US "Catholic" President authorized and encouraged the coup that led to the assassination of his brothers. Now, the family were despised for promoting Catholicism as the state religion (something that of course Vatican II dumped, with "Dignitatis Humanae"). I suspect that the "reports" of their brutality against Buddhists were largely propaganda efforts, with even a touch of "let them eat cake" nonsense attributed to one of their wives. What likely happened in those incidents was similar to what they did in Iran recently, where the US and Israel shipped arms into Iran (via the Kurds, as Chump let it slip a little while ago), and where they sponsored a violent ιnѕυrrєcтισn. Similarly, the "Buddhists" were undoubtedly mostly Communists and Commie agents, just as the family asserted, and I'm fairly convinced that the whole Buddhist "self-immolation" stunt was orchestrated by the Commies. They used these agent provocateurs to whip up hatred for the Catholic "rulilng" familiy, and then when the latter crack down, the propaganda turns them into the brutal oppressors. I'd love to get the real truth behind all of that.
In any case, the adulterous dirtbag JFK (and his brother largely instigated the persecution of Father Feeney) ... who basically got into the White House by running on a "separation of Church and state" platform, or else he would never have gotten enough of the Prot vote to win ... JFK authorized the "military" coup, aka the Commie coup ... and that actually led to the Vietnam war.
Now, the coup led to the assassinations of Diem family on November 2, 1963 ... but then, per the "live by the sword, die by the sword" JFK was himself αssαssιnαtҽd on November 22, 1963.
Reportedly, the villian LBJ was actually strongly opposed to fomenting the coup that resulted in the assassinations, and after having visitied with Thuc, he referred to him as the "Winston Churchill of Asia". To JFK's credit, however, he reportedly wnanted Diem to be exiled and almost physically shaken when he heard that they had been murdered.
I think that JFK feel for the whole Buddhist "self-immolation" stunt that he authorized the coup ... and I would love to find the true story of that. I doubt it had anything to do with the poor Buddhists not being able to publicly practice their false religion ... but that somehow it was a Commie-orchestrated or instigated stunt to have precisely the effect that it did have.