My read is that started as anti colonialism against the French but then the big powers took sides so the Vietnamese started fighting each other.
The sad thing is that a lot of problems could have been avoided if the Americans in the 50s wouldn't have been so scared of any kind of communism or socialism. They messed up Iran, they drove Egypt into the arms of the Soviets, and they may have even had friendlier relationships with Fidel Castro.
Ah but you forget that the economic exploitation of the former colonies was supposed to continue. It is not so much communism that frightened the West as it was nationalism.
Vietnam’s independence took a back seat after WW2 for the US because France made regaining its colony contingent upon playing along with NATO. France floated the idea of aligning with the USSR to scare its Western allies. So for the US it decided Europe was the more important sphere.
The US’s main strategy with the communism was one of containment - see George Kennan’s Security Council memo.
Why containment? Because the USSR was exporting revolution. The US could take the stance of doing nothing, but then the USSR would have free rein. And it wasn’t a matter of “let the people in those countries go communist if they want to”, because with USSR support a minority of people could impose communism on a population that wasn’t interested in it. Hence containment - just slow or stop other countries from going communist by matching what the USSR was doing - bankrolling and training political groups in those countries.
So doing nothing with Vietnam and letting France regain their colony aligned with containing further expansion of communist in South East Asia. If Vietnam went back to a French colony, then communism wouldn’t take hold (or it would at least be difficult for it).
The sad thing is that a lot of problems could have been avoided if the Americans in the 50s wouldn't have been so scared of any kind of communism or socialism. They messed up Iran, they drove Egypt into the arms of the Soviets, and they may have even had friendlier relationships with Fidel Castro.