First contact is made on a new planet. The natives attack with spears. Rules of engagement are proportional response. Natives invent arrows, guns, cannons, tanks, missiles; the response is always just enough to subdue the natives.
Eventually the decision is made to set off a nuke, at which time the natives agree to peace talks for the first time. Their message is, “How could you have been so cruel? You always let us think that you were only a half a step ahead of us, so if we tried just a little harder we could beat you. If we had known that you could annihilate us at any time we wouldn't have kept fighting all these years. All these senseless deaths could have been avoided!”