Why does the narrator lie to his daughter, and how does he justify it?

(The things they carried)

The narrator's nine-year-old daughter, knowing that her father writes war stories, asks him if he has ever killed anyone. The narrator says no but resolves to tell her the truth when she is grown. He then recalls how he killed a young man in Vietnam. This is just one of the many examples related to war that prove most actions have both ... many people like Tim O'Brien discover good and bad things about themselves through war ... A: In the beginning of the story he is "ambushed" by his daughter's question ... Q: What vision does the narrator sometimes see in his mind?