This book brings a world-class team of authors to examine United Nations actors, tools, and issues associated with the changing nature of the environment in which it operates, the ways in which it has responded and might respond to technological and political problems, and the questions and difficulties that arise for the world organisation. Issues covered in the book include doctrinal questions on the use of force, the regional dynamics of nuclear proliferation, and the growing concern that nuclear order established by the treaty on the non-proliferation of Nuclear Weapons (NPT) may collapse or simply be overtaken by events.