Robots formerly belonged to the realm of fiction, but are now becoming a practical issue for the disarmament community. While some believe that military robots could act more ethically than human soldiers on the battlefield, others have countered that such a scenario is highly unlikely, and that the technology in question should be banned. Autonomous weapon systems will be unable to discriminate between soldiers and civilians, and their use will lower the threshold to resort to the use of force, they argue. In this article, I take a bird’s-eye look at the international humanitarian law (ihl) pertaining to autonomous weapon systems. My argument is twofold: First, I argue that it is indeed difficult to imagine how ihl could be implemented by algorithm. The rules of distinction, proportionality, and precautions all call for what are arguably unquantifiable decisions. Second, I argue that existing humanitarian law in many ways presupposes responsible human agency.