Military research and development (R&D) at the nanoscale have gone on at a moderate pace for about two decades, more or less in parallel to civilian work. As in other military areas, the USA made the greatest effort. In recent years, the USA has strongly increased its military R&D for nanotechnology (NT) – a decision that may or may not be followed by other countries. Because the USA sets a clear precedent and because military R&D is most transparent there, the US efforts will be described in some detail in Section 3.1. For other countries, much less information is available. Some other countries are treated in Section 3.2, and their efforts are compared to the US ones in Section 3.3.