In The Things They Carried, most of the men and women refuse to talk about the war, either during or after the war. Martha refuses to listen to Cross' letters; the lady at the reading doesn't understand a "war story" from a "love story"; the "dumb cooze" refuses to listen; Lemon's sister never writes back; Bowker drives around in circles: he can't talk to his father, his old girlfriend, or even O'Brien. He kills himself because of his inability to communicate.
Mary Anne, after she kills, refuses to talk to Mark Fossie: Mary Anne tells her boyfriend, "Not a word"..."We'll talk later," a pre-emptive communication strike usually reserved for a tired male coming home to a chatty wife. That "later" never comes, as Mary Anne only "mumble[s] out a vague word or two," and by the end her last words are "impassive," resigned, "not trying to persuade" (O'Brien 112). Soon, she does not speak at all, choosing to "disappear inside herself" (O'Brien 105). Like the earlier six-man patrol who "don't got tongues," (O'Brien 72). In the end, Mary Anne becomes a non-human, forsaking communication for the law of the jungle.
All of these soldiers become animals, more of less, in the jungles of Vietnam. Mary Anne goes out on ambush with the Greenies, who were not "social animals," but simply "animals" (O'Brien 92). They are the equivalent of the VC enemy since they are from the jungle and do not speak a discernable language. In fact, the Greenies "did not speak" at all, using only non-verbal cues. After Mary Anne’s long absence, the Greenies are confronted by the medics, and instead of dialogue, the Greenies only nod and stare. Ironically, the medics expect as much, as they do not even engage in argument. Both parties avoid verbal communication, like two groups of animals sizing up each other.
O'Brien is the only one, it seems, who can talk about the war, but only long after the war (20 years). But even his talk has lies in it. He tells his daughter that he didn't kill anybody. He says he killed the man he killed and then he says he didn't. In the novel, O'Brien subverts communication: he chooses lies to tell the truth. Fiction is his only outlet for telling a true war story. But, it takes 20 years for the truth to be told.