Nanotechnology and related technology trends are disruptive and transformative technologies that pose fundamental questions for security in the international system of the 21st century. However, to date there has been little analysis of these issues within the still underdeveloped context of social and ethical concerns about nanotechnology. This paper briefly surveys military NT efforts in the United States, the nation that is leading where others may follow. It also discusses the broad range of potential uses of NT by armed forces, and suggests some of the most pressing problems that could result.