Published online: 08 January 2015 Contrary to the common claim that jus in bello proportionality is an obscure and intractable principle of modern warfare, this paper shows that proportionality balancing has a central role to play in assuring efficient military operations with a minimum number of casualties. Military commanders can and should want to understand proportionality as a requirement to measure military advantage in terms of lives saved and direct their operations toward the most life-saving operations. The targeted killing context in particular highlights the advantage of making proportionality analysis a central component of military strategy in asymmetrical conflicts.