In The Things They Carried, Tim O'Brien says that storytellers are those with long memories--they keep the past alive, even the lives of the dead. That's why Norman Bowker, Jimmy Cross, Rat Kiley, and O'Brien's own daughter go to O'Brien as a source for making sense of the chaos and senselessness that was the war: his stories serve to protect and validate memories and truth.
As a piece of metafiction, O'Brien's writes stories about stories: he writes stories that take place before the war ("Lives of the Dead"), during the war ("Sweetheart of the Song Tra Bong," and after the war ("Speaking of Courage"), all of which attempt to "heat up the truth"--to paradoxically find more truth in fiction than so-called "realism."
For O'Brien, Vietnmas was an organic, living place, and he has a primordial connection with the land, "Vietnam was full of strange stories" (O'Brien 89). For example, Mary Anne in "Sweetheart of the Song Tra Bong," becomes a killing machine after taking a dip in the jungle water. I find "Sweetheart" very biblical, a creation story and a cautionary tale like the fall of man in Genesis. Others might find it mythological, an homage to the epic heroines of Vietnam yore. Still others find the story rooted in storytelling and gender. For Rat Kiley, it is a means of heating up the truth. For others still, it is escape. It is O'Brien's mutli-faceted and paradoxical approach to character and story which allows "Sweetheart of Song Tra Bong" to flood its banks and envelop so many readers, despite its inherent unbelievability.
After all, in "How to Tell a True War Story," O'Brien says:
I want you to feel what I felt. I want you to know why story-truth is truer sometimes than happening-truth. (179)
The best and only way to "make the stomach believe" any story is to tell it and re-tell it and revise it and change it until it works on a gut level, even if it takes twenty years to finally get it right and some of the "facts" have been lost along the way...