The time has come to draw lessons from the war in Afghanistan. One major concern is how the U.S. military ought to deal with civilians who are sporadic combatants, and civilians who act, part of the time, as support forces for combatants (by serving as intelligence agents, manufacturing ammunition and bombs, supplying provisions and transportation, and so on). Discussion of this topic has often focused on ways to deal with those civilians after they have been caught fighting us and whether they should be treated as soldiers or as criminals, a matter that has not been resolved. (My own position is that they should be treated as a third category: as terrorists, subject to distinct rules and authority.) This article focuses on an earlier phase: when these civilians are still acting as combatants or supporting them. This article makes the case for a major change in the basic normative precept involved and for a new Geneva Convention, both needed in order to shift the main onus of civilian casualties where it belongs: to those who engage in combat (or help those who do) without adhering to the rules of war, which require that they separate themselves from peaceful civilians. While the U.S. and its allies should do their best to minimize collateral damage, instead of accepting the basic precept that we are the main cause of civilian casualties—highlighting our mistakes, repeatedly apologizing, and seeking to make amends—we should stress that insurgents who violate the rules of war are the main source of these regrettable casualties