So Vietnam is a very interesting situation to look at from a more neutral standpoint. There aren't really any good guys per say in that war. It was nasty as fuck. America was supporting some rich asshole dictator with a harem in the south who just assumed to get rich off of the war rather than actually winning and in the end he was assassinated for it and his country was overrun with the communists. On the other hand you've got foreign educated revolutionary Ho Chi Minh in the north who has ostensibly noble motives which engenders a very rabidly loyal fighting force but who is willing to perpetrate whatever atrocities are necessary to promote the formation of the people's republic as is customary with the communists, though admittedly he is far more palatable than the Mao's or Stalins of the world.

Vietnam I think was basically the first time that the Americans started to wake up to the facets of war spelled out in "The Principles of Oligarchic Collectivism" which we started to see as early as the Korean war but we still had some right assholes like McArthur in there ready to kick ass and take names.

Fonda's crime there isn't so much saying "hey guys maybe we should rethink this war", she basically went over and played propagandist for the northerners did the photo shoots and all that and bought their propoganda that the northerns were all just peaceful farmers while her countrymen were literally getting forced to go over there just to get carved up and spit out by any matter of Vietcong traps. I've been there. I've seen them. They're very resourceful in their killing of Americans. You must give them credit for improvising.

Now the Vietcong were certainly justified in protecting their homeland, but it's not Fonda's homeland, and she wasn't really justified in going over there during the war and basically playing Tokyo Jane for them.