Nuclear power is the only proven new energy technology that can meet energy demands. A technologically competent person could design a workable fission device, yet it would be difficult for terrorists to obtain the necessary fissionable material. There is no known black-market in stolen fissionable material. The costs of obtaining such material and the difficulty involved in constructing a bomb will probably ensure that terrorist groups will not attempt such an undertaking. European nations lag far behind the United States in developing adequate physical security systems for transporting nuclear material. Exposing a population to radioactive materials is possible, although plutonium is not one of the most toxic substances known for that purpose. Authorities in most countries have opted for technical solutions to the problem of nuclear vulnerability, generally by denying access to the target. Counterthreat programs, such as the Nuclear Emergency Search Team, have been developed, and efforts are underway to develop methods of corrupting or despoiling nuclear material so that during transit it would pose hazards to terrorists but would be unsuitable for manufacturing nuclear weapons. A total of 75 reference notes are provided.