You get orders to do a thing (“blow up that orphanage soldier!”)

You ask for clarification (“that looks like a civilian target, do you mean the outpost next to it?”)

Get claification that confirms unlawful order (“No the orphanage full of kids, level it.”)

You are OBLIGATED BY YOUR DUTY TO INTERNATIONAL LAWS OF WAR to reject the order (“Negative, I cannot do that”) and to report others who obey unlawful orders, outside of your chain of command if neccesary (“Fine, I’ll get someone else to destroy it, you’re finished.”)

Then you’ll likely be pulled from your unit, and face court matial where the situation will be investigated like most other court cases. (“There was an outpost nearby but the orphanage was not a legal target”)