A central theme of the novel is the enormous gap between the romanticized view of war and its grim realities. Over the course of the book, Quan comes to realize that war is not an heroic struggle for freedom, as the authorities would have him believe, but a brutal, de-humanizing bloodbath which degrades and destroys.
Quan has been taught to hate Americans for what they've done to his country, but because of his experiences of war, he comes to see them in a completely different light. The American soldiers, no less than their Vietnamese opponents, have been exploited by their superiors, led into a conflict which is ultimately not in their best interests.
It may come as a surprise to find that a foot soldier in the North Vietnamese army should have the same experience of war as many of his American counterparts. Yet this only serves to underline the universality of the book's overriding theme: that no one nation or culture is immune from the temptation to glorify war and to overlook its horrifying reality.