Book excerpt: This primer provides an overview of the technical background needed to understand today's nonproliferation issues. It describes all the existing types of weapons of mass destruction and examines the threats they pose and their implications for regional and international security. The authors identify countries that have, or may have, programmes to develop such weapons, describe the technology needed to continue such programmes, and examine the extent to which these programmes violate existing international agreements. They also outline existing unilateral and multilateral measures designed to curb proliferation and discuss new measures that could strengthen current nonproliferation efforts.