Why did the u. s the french in their fight against hochiminh?

The US was certainly anticommunist and certainly a French ally but it is described in Bernard Fall's "Hell in a Very Small Place" as a gradual process.

s the president shall be commander in chief of the army and navy of the united states, and of the militia of the several states, when called into the actual service of the united states; he may require the opinion, in writing, of the principal officer in each of the executive departments. sooo yeahhh

explanation:

the indians crossed artificial boundaries, setting the stage for conflict