My problem with Chomsky is he uses selective omission to make his case, and his case is always the same, America is the proactive source of all problems in the world. (This is far too simplistic, as America is often a re-active power.)
The complicated history of Vietnam or Japanese Imperialism is a different subject to Chomsky's selective omission of facts that do not support his case that the US is always caused of such conflicts.
But just quickly, Ho Chi Minn probably would have won elections, why: because all political opposition to him in the North hand been silenced or eliminated, all Catholics purged or forced to flee to the South. Indeed, Ho never held a democratic election ever in any territory he controlled. Ever.
Now the regime in the South would have practiced fraud too, so the idea that any real election could be held as demanded under the Geneva Accords was a sham, and the US knew it. In fact in the early 70s South Vietnam did have real elections, North Vietnam never did or has since.
China; your argument proves my point about Chomsky, the US is not the active agent in China, it first wants only to deter Japanese imperialism through sanctions and negotiation, and it is Japan that is driving events with aggression. (To the contrary of Chomsky's argument).
It is true the Communists did gain popularity by being the major force to fight Japan in China, mostly because they did not control urban centers and had developed a strategy of rural fighting the that worked relatively well against the Japanese but that does not validate Chomsky's thesis that the US provoked the war with Japan, to the contrary it proves the opposite, that the US did not want to get bogged down controlling directly controlling territory through direct invasion. The US was taking the path that would most hurt the Japanese while minimizing their control of China.
US choices were not good there; they had to support any group who would oppose Japan while thinking of future communist influence.
Some times your options are not good, but Chomsky's argument is that the US is both controlling and causing events. The history of China in WWII proves just how reactive the US was being.