The justice and injustice of asymmetric wars were hotly debated in the years preceding the publication of the fifth edition. An asymmetric war is one between “a very strong and a very weak military force: a high-tech army against a low-tech insurgency” (xx). Walzer maintains that asymmetric wars do not cause significant revisions to just war theory: Insurgents should not initiate violence before a political struggle because even if the cause of the insurgents is just, it is possible to undermine that cause via the use of unjust means. Although the stronger force might be difficult to attack frontally, there are typically some vulnerable military targets. This is better than deliberately exposing civilians to violence. The stronger army should not indiscriminately target civilians even though they are fighting a non-uniformed enemy, and soldiers must accept some risk in order to protect civilians. However, when such risks are taken and “civilians are killed because they are being used as cover or deliberately exposed” (xxi-xxii), then the stronger army has done all it can do.

Walzer explains the ways that ordinary people argue about the morality of war and elaborates on the terms used in such arguments.