She may have committed treason by virtue of the radio broadcasts that she made on behalf of the North Vietnamese government. She encouraged American pilots to return to base without dropping their bombs. As an interesting comparison, here's a quote from Kawakita v. US (343 US 717) detailing treasonous comments made by the defendant:
Evidence of what petitioner said during this period concerning the war effort and his professions of loyalty, if believed by the jury, leaves little doubt of his traitorous intent. "It looks like MacArthur took a run-out powder on you boys"; "The Japanese were a little superior to your American soldiers"; "You Americans don't have no chance. We will win the war." "Well, you guys needn't be interested in when the war will be over because you won't go back; you will stay here and work. I will go back to the States because I am an American citizen"; "We will kill all you prisoners right here anyway, whether you win the war or lose it. You will never get to go back to the States"; "I will be glad when all of the Americans is dead, and then I can go home and live happy." These are some of the statements petitioner made aligning himself with the Japanese cause. There was also evidence that he said that the prisoners would never go back to their wives and their families, that Japan would win the war and that he would return to the United States as an important man, that Japan would win if it took 100 years, that the Japanese were superior to the Americans and if the American Army had Japanese officers, they could whip the world, that there were more American boys who would be available to do the work, if the present prisoners were too weak to work. And on the day the work at the camp ended after Japan surrendered he commented, "You American bastards will be well fed" or "you will be getting fat from now on."
She clearly fulfilled the overt act requirement, as required by the Constitution, by making at least one of those broadcasts. The real question is whether she fulfilled the intent requirement, which demands an intent to betray the United States. Here's an excerpt claimed to be from a House investigation in 1972 (unable to independently verify at the moment):
"One thing that I have learned beyond a shadow of a doubt since I've been in this country is that Nixon will never be able to break the spirit of these people; he'll never be able to turn Vietnam, north and south, into a neo- colony of the United States by bombing, by invading, by attacking in any way. One has only to go into the countryside and listen to the peasants describe the lives they led before the revolution to understand why every bomb that is dropped only strengthens their determination to resist. I've spoken to many peasants who talked about the days when their parents had to sell themselves to landlords as virtually slaves, when there were very few schools and much illiteracy, inadequate medical care, when they were not masters of their own lives.
But now, despite the bombs, despite the crimes being created- being committed against them by Richard Nixon, these people own their own land, build their own schools- the children learning, literacy- illiteracy is being wiped out, there is no more prostitution as there was during the time when this was a French colony. In other words, the people have taken power into their own hands, and they are controlling their own lives."
The above citation comes from this link.
http://www.1stcavmedic.com/jane_fonda.htmHere's a little evidence, hopefully credible in the case of the latter citation, to help you decide for yourself. Enjoy.