According to you all an enemy has to do is put some civilians near every target and then it's a crime to hit that target because the other side knows that civilians are there. This is unreal and you don't believe it, because you also write further in your post about 'out of proportion'. So I think you understand that civilians may be targetted. When exactly is presumably what the book is about. As for proportion, the amount of force that may be used should be proportional to the needs of the military, not to number of dead on your side. One can kill enemy up to the point needed to achieve legitimate military goals, even if the number of deal enemy is more than the number of your own dead.
Roadside bomb kills five border officers in western Iraq (AP)
from the article: Police release rabbi arrested for inciting to kill non-Jews