Under international law, they have to be treated this way and not charged with crimes. As long as a soldier is acting under the laws of war, they can't be tried

Under international law, they have to be treated this way and not charged with crimes. As long as a soldier is acting under the laws of war, they can't be tried for violations of ordinary criminal law. They can only be held for the duration of hostilities and then must be returned to their home country. So they really aren't subject to domestic law at all.