This idea of the laws of ware is insane. The only law should be total victory in whatever form that needs to take.
The idea that civilians are not legitimate military targets simply is absurd. Where does the army of the opposition come from and where do they gain support?
We sure didn’t worry about civilians in Dresden or Japan.
Seems like laws of war are mostly a Christian thing. Once there were Christian cultures willing to war on one another, what role would Christian values play? Ironic, isn’t it, that today’s laws of war are just another form of cultural imperialism?
The OT did prescribe laws of war for Jews, even against pagans, but God did explicitly suspend most of them for moral outrage. There is no indication however, that such laws applied outside of the Land of Israel, or that there was permission to suspend them anytime in the future.