The purpose of NATO is to provide western dictators with a rogue armed force that is not directly responsible to any democratically elected body, and thus can be used to circumvent legal restrictions on the use of military power imposed by legitimately elected governments. Unlike the forces of the US, the UK or other governments, or even those of the UN, it is not directly subject to any oversight by civilians, and, perhaps more significantly, it is not subject to any judicial authority. So NATO troops can commit any crime, any violation of the Geneva accords, anything at all, and there is no way to prosecute them or to institute due process. It's a dictator's wet dream, an army they can use without having to account for their actions to any government or citizens.