In the history of humankind, any new scientific discovery has shown the risk of a “dual use” for peaceful purposes or for warfare. In regard to non-conventional weapons, the recent exponential development of nanosciences and nanotechnology can provide efficient tools for counteracting these threats, by improving the detection, protection, and decontamination capabilities in the field of CBRN defence. Nevertheless, these disciplines also may offer novel, uncontrolled means of mass destruction, leading to the synthesis of new, intentionally toxic systems. Furthermore, several points of concern are linked to the new concepts of “nanotoxicology” and “nanopathology: If a multidisciplinary approach is needed to study nanosciences and nanotechnologies, a multidisciplinary approach also is needed to have a strict control on potential illegal uses of nanosystems. Experts active in various fields, such as academic, industrial, military, and health protection institutions, must work cooperatively to constantly follow the state of the art, note which kind of critical emerging technologies may lead to illicit uses, and control the diffusion of hazardous nanosystems that may be potential precursors of weapons of mass destruction, and cooperate with CBRN emergency prevention organizations in order to plan suitable countermeasures. This presentation will cover some examples of nanosystems applied to defense from non-conventional warfare agents and answer questions regarding potential misuses of basic nanoscience and nanotechnology findings.