Israel: Where is the line between self defense and atrocities?

http://www.alternet.org/world/open-letter-israels-supporters-where-do-you-draw-line-between-defense-and-atrocities?akid=12145.294211.b4Vbph&rd=1&src=newsletter1016127&t=5

This raises the basic question: as a human being, where do you draw the line? How do you justify your support for mass misery inflicted on hundreds of thousands of innocent civilians? The bombing and shelling campaign, whatever its stated intent, has not only murdered 1,400 civilians and maimed thousands more, but destroyed hospitals, schools, businesses, and Gaza’s only power station, plunging 1.8 million Gazans into darkness and depriving them even of drinking water, created over 400,000 refugees, and traumatized a U.N.-estimated 373,000 children. Your own integrity requires that you at least acknowledge the facts rather than, as so many of Israel’s supporters do, accept at face-value Israeli claims that it sought to avoid civilian destruction.