According to some military visionaries, warriors will wield rifles that fire small self-guided missiles, dispatch flying mini-robots and micro-sensor nets as scouts and sentries, and carry devices that can gather water in any environment. They will be networked to tactical command through helmets that provide an "augmented reality" overlaid with information and instructions. Even nanotechnology (NT) provides no immunity to conventional explosive devices; heavy-caliber ballistics, chemical and biological agents that manage to penetrate the layers of protection, or nuclear weapons. DARPA aims at cognitive computing systems that learn and decide autonomously in new situations. The security of all sides is served better if the more dangerous applications of NT were reliably and verifiably contained.