this was the point made by Captain Willard in Apoc Now, if you recall and it wasn't simply that it militarily negating. it was symptomatic of a lie, using a falsehood to cover up a collective guilt.

"the more they tried to make it just like home, the more they missed it; but I knew it wasn't there anymore.."

and of course these turning points, these deeper insights into the futility of the war and what it was failing to achieve, are the key points in the film. The tragic irony of the American presence in Vietnam is imo summed up in the sampan scene where the native boat is shot up because the Chief wants to inspect it for contraband, and the girl tries to hide her puppy. When Chef discovers she's still alive despite being cut down by .50 cal, and the crew want to take her to a vietnamese post for treatment, Willard calmly steps on the boat and shoots her in the head? as he walks away he says to the Chief,

"I told you not to stop.."

He has a mission to fulfill, and she;s going to die anyway, he cuts out the time-wasting and finishes her off. He's personally disgusted by what he;s seen, and doesn't want her to suffer anymore. Killing doesn't bother him, he's an assassin. He's both a vehicle for us to "witness" and a conduit for the director's intent. So he says to us,

"we cut them in half and offer them a band-aid. it was a lie, and I was so sick of lies.."

Arch you can correct me if I misquoted (again)

it's an incredibly powerful revelation, almost a catharsis if you will, and opens up new depths of meaning for the rest of the film.