The US government appears to be using drones to launch air strikes inside Pakistan. This article details uncertainties regarding the ethical soundness of these strikes and highlights the consequent need for greater official transparency. Available evidence is assessed in the light of traditional ethical requirements that the use of force is beneficial to a legitimate military objective, that it discriminates between combatants and noncombatants, and that it generates harm that is proportional to the expected military benefit. The murky picture that emerges is an inadequate foundation for determining whether US drone strikes in Pakistan constitute a just or an unjust use of force. Arguably, however, the very persistence of doubt on this point undermines international norms on the use of force and the reputation of the United States as a champion thereof. The US government should therefore either refrain from drone strikes or explain publicly how they are beneficial, discriminate, and proportionate.