Dramatic advances in weapons technology over the past two decades have led to a revolution in military affairs. Robotics and cyber weapons have used real-time information and communications to produce precision that has reduced casualties and blurred the line between war and peace. Critics fear that these developments will encourage nations to resort to force more often; they call for international agreements to ban the new technologies. This Essay argues that efforts to limit the use of such weapons are both misguided and counterproductive. New military technologies will advance humanitarian aims by reducing civilian casualties and the overall destructiveness of war. A rationalist approach to war even suggests that these weapons will create more opportunities for the settlement of international disputes with less use of force.