Gross is known for bringing a sharp intellect and a keen moral sense to the perplexing character of modern war. In his latest book, he considers the prominent role of civilians in contemporary conflicts -- including wars initiated to protect the welfare of oppressed civilians and those in which enemies use noncombatants as shields or targets. Against such unrestrained enemies, Western countries face the dilemma of whether to abandon their past prohibitions on such practices as torture and assassination. Gross traces the processes by which exceptions, such as "enhanced interrogation techniques" and targeted killings, take hold and then start to become accepted, especially if they are considered effective. In exploring the "constant interaction" between military necessity and humanitarianism, he notes that traditional norms regarding the protection of combatants and noncombatants have considerable influence, even when governments start to slide down the slippery slope away from them. Gross' wariness of dogmatism ensures that there are no easy answers; this is a book that will keep you thinking.