Around a year go, Ben Carson, a candidate for the Republican nomination for president, endorsed war crimes on the grounds that “there is no such thing as a politically correct war." Many thought he was nuts. But in fact, he was right. There is no such thing as a war without crimes. If you go to war, you will commit many, many crimes.

The thing is this: There are really no rules in war, no order, no conventions. War is about only one thing: winning. This is why it must be avoided at all costs. We must never have the illusion that war is something that can be rationally managed. Once it begins, the gates of hell are flung open: the killing of children, the destruction of crops and natural resources, the detonation of chemical weapons, the pillaging, the torture, the rape.

And this is essentially the message at the heart of A War, a Danish film that’s a nominee for the Oscar’s best foreign language film. Set in Afghanistan, the film is about unit of Danish soldiers under the command of Claus Pedersen (Pilou Asbæk). Pedersen, who has a wife and children, spends much of the first part of the film doing the best he can. He thinks things over, he cares about his soldiers, he is always alert. But then things spin out of control, and he has to face the consequences back home.

But the thing is this: No one is really right in this film. Why? Because it is impossible for war to be morally clear. War is like the night when all cows are black. War rewards only the bad and the ugly. In war, everything is permitted.