With the Israeli bombardment of Gaza right now, I have been seeing a lot of misinformation in social networking media and the news, and hearing a lot of misinformation in conversation, about humanitarian law and ethics in such situations.
Here are some resources. It can be very helpful to familiarize yourself with some of these, especially the first two, rather than simply repeating what "everyone knows" about the ethics or legality of the current situation.
War & Law: Conduct of Hostilities
International Humanitarian Law and Terrorism: Questions and Answers
The Rules of War: What Do We Really Know?
Red Cross Survey on the Rules of War
80% of Young Americans Believe More Education Is Needed on Rules of War
Exploring Humanitarian Law: A Guide for Teachers
War and International Humanitarian Law, International Committee of the Red Cross/Red Crescent
Some additional resources, if you'd like to do something positive:
afghans for Afghans
a humanitarian project in partnership with the American Friends Service Committee (http://www.afsc.org/), and in the Red Cross Knitting Tradition (http://www.afghansforafghans.org/red_cross.html)
Christian Peacemaker Teams
"Getting in the way of violence"