The Diem coup was a mistake for Kennedy... but the plan came from the generals in Vietnam to the USA,
not the other way around.  Diem was never legally elected as head of the country.  Diem's opposition to the
Buddhists was tearing the country apart and had Diem stayed, I doubt the war would have gone much differently.
Diem's ouster was followed by successive military 'regimes' none of which represented the will of the people.

What the USA should have done in Vietnam was to sanction the Geneva Convention Elections, and worked with
the leaders who were elected.  Most likely that would have been Ho Chi Minh.

Ho could have been turned to our ally  (and stayed a communist) by the USA siding with Vietnam against their
enemy China.  

the kennedys were making war $$$$$$$$ too.....

Quoted from Box A Rox

The Diem coup was a mistake for Kennedy... but the plan came from the generals in Vietnam to the USA,
not the other way around.  Diem was never legally elected as head of the country.  Diem's opposition to the
Buddhists was tearing the country apart and had Diem stayed, I doubt the war would have gone much differently.
Diem's ouster was followed by successive military 'regimes' none of which represented the will of the people.

What the USA should have done in Vietnam was to sanction the Geneva Convention Elections, and worked with
the leaders who were elected.  Most likely that would have been Ho Chi Minh.

Ho could have been turned to our ally  (and stayed a communist) by the USA siding with Vietnam against their
enemy China.  

Diem would not have been the first nor the last questionable (non democratically elected leader) that the US chose to support during the Cold War.  The sad fact is that the US had to support a number of these questionable leaders in order to stem the advance of the Soviet Union and Communist China.

I am not alone in believing that Diem's assassination did alter the course.  It destabilized South Vietnam and made it necessary for the US to become even more militarily involved in the region.   Bottomline -  President Kennedy blew it when he ordered the coup against Diem and -in the process- was complicit in the assassination of an ally.   Furthermore, the writers of the fictional/fairy-tale "American Camelot" were only interested in making President Kennedy look good and foisting the blame for Vietnam off on Lyndon Johnson.