This article is divided into three parts. First, it reviews the legal obligation to distinguish between combatants and noncombatants in war, the historical evolution of this principle, and the challenge state militaries face in observing this norm in asymmetric conflicts. The second section analyses criteria developed by the International Committee of the Red Cross (ICRC) for distinguishing between combatants, civilians participating in hostilities and civilians protected against direct attack. Such criteria were developed for and published in the ICRC's 2009 report entitled "Interpretive guidance on the notion of direct participation in hostilities under international humanitarian law." The final section analyses restraints on the use of force during asymmetric conflicts between sophisticated state militaries and poorly trained and equipped non-state actors. In doing so, this article will demonstrate the logic of more restrictive restraints on lethal force during irregular warfare. In particular, this article contends that international human rights law should control lethal force during occupations or non-international armed conflicts where a party controls significant territory. Such a change would require that security forces exhaust non-lethal measures before resorting to deadly force, which could result in fewer noncombatant casualties at little additional risk to security forces.