The most realistic depiction of war, at least that I've heard him discuss, is Saving Private Ryan. He says it captures everything except the "smell of death." There is a smell, he says, that can't be described tied to war and death.

He also said that he watched MASH (the film) with some high level officers while on tour and they loved it. Supposedly, it was good at capturing some of the quirky, funnier aspects of the day to day lives of some Korean War soldiers.