Civilian casualties in Halacha

This week's parsha וישלח has the story of the brothers and Shechem. The mefarshim are bothered by the brothers killing of everyone in the city not just Shechem and Chamor. The Maharal justifies the actions of Shimon and Levi, asserting that the Torah sanctions waging war when a nation attacks us. In such circumstances, we are permitted to respond to the other nation’s provocation. In responding, we attack the other nation and do not distinguish between the guilty members and the innocent members of that nation. Thus, Shimon and Levi appropriately responded to Shechem’s aggression. Once they responded, they were permitted to attack the entire nation, because this is the manner in which war is waged.This Maharal is quoted l'halacha by a number of modern day poskim including Rabbi JD Bleich who writes:

"Not only does one search in vain for a ruling prohibiting military activity likely to result in the death of civilians, but to this writer’s knowledge, there exists no discussion in classical rabbinic sources that takes cognizance of the likelihood of causing civilian casualties in the course of hostilities legitimately undertaken as posing a halakhic or moral problem."

This position is echoed by Rav Shaul Yisraeli, Rav Asher Weiss, Rav Herschel Shachter and others. According to them not only are civilian casualties not prohibited, it is prohibited to endanger Jewish soldiers in any way to minimize civilian casualties.

This approach is diametrically opposed to international law which treats civilian casualties as a war crime in many cases.