If a country is pursuing what it sees as self-defense, where should it draw the line in terms of civilian casualties?

Deliberate Civilian casualties are never acceptable. Civilians and children are not adversaries in senseless wars

killing children because the children didn't do nothing wrong and should keep the right to live life.

There should be no citizen casualties in self defense because you should be protecting against attackers not harmless people

It should draw the line in civilian casualties when those people are innocent children and women.