Civilians are part of the war effort. We have deliberately targeted civilians, we should target civilians and if we want to win then we should seek to obliterate societies if we hope to achieve victory.
Oh and that was simply me stating facts. This is the bad news.
ISIS targeting us should be expected, them succeeding should be considered a certainty and all the wailing/gnashing of teeth will not change that. Additionally if we search our past then we know that civilians are legitimate targets. Stalingrad, London, Berlin, Tokyo, Washington DC, Atlanta and many other cities have been burned to the ground.
Have you ever wondered why our "modern" way of war fails? Its really quite simple. Its because we have arbitrarily taken the ability to strike the support system for insurgents and/or the supply lines from their proxies. That's why they should be targeted. If not then insurgencies that should be crushed in a year, are instead generational wars that last for 20 or more years. Our weapons are fine. Its our strategist that have failed us. They have pushed a warfighting concept that is not meant to win, but to simply feed the military industrial complex (God help me....I'm sounding like a lefty!).