Military commanders in wartime have moral obligations to abide by international norms and humanitarian laws governing their treatment of noncombatants. How much risk to their own forces they must take to limit harm to civilians in the course of military operations, however, is unclear. The principle of proportionality in the law of armed conflict all but necessitates that they make a utilitarian calculation: potential harm to civilians must always be balanced against military value when considering actions that could hurt innocents. In asymmetric conflicts, such as most counterinsurgencies, information flows, collaboration, and ultimately the support of the local population can be key to achieving strategic objectives. Thus, limiting casualties to noncombatants and other actions that alienate the population in these types of conflicts is a key part of a winning strategy. The concept of “courageous restraint” was created to express this principle to NATO and U.S. forces fighting in Afghanistan.
How much risk combat troops must accept in order to avoid harming civilians has long been central to moral and legal arguments about just conduct during war, or jus in bello. In his seminal book Just and Unjust Wars, Michael Walzer argues that it is a state’s duty to accept greater risks for its own military forces as a means to limit harm to noncombatants in the course of armed conflict. He provides a vignette from a World War I British soldier’s memoir for context in supporting this assertion. In this particular incident, Walzer describes a dilemma faced by British troops as they attempt to clear a French town of German soldiers hiding among some of its dwellings. When entering a home, the British soldiers had the choice of whether or not to shout a warning before throwing a grenade down the cellar stairs. This warning would alert civilian noncombatants that may be hiding there and give them the opportunity to make the British soldiers . . .