One of the key concepts regarding national authority is called “The monopoly on violence”. The idea that any threat or use of force from a nation comes with the sanction of the state, and not by other actors. Without a monopoly on violence, other states would have no reason to trust a state when it comes to negotiating peace treaties, declaring war, etc.

Its one of they key reasons why peace deals are so hard to broker in the Middle East. It makes no sense to declare peace with a faction when as soon as you do, half of its membership splits and forms an all new faction to keep fighting.

Civilized states have a responsibility to ensure its citizens are not engaging in foreign wars.