The recent political and economic changes to the world have made it possible for terrorists to threaten, or complete an attack, using sophisticated weapons of mass destruction. Weapons, once limited to ownership and use by national governments, may fall into the hands of terrorists who have both the financial and technical ability to acquire them.

Radiological refers to radiation or materials that emit radiation such as industrial material. A terrorist may use radiological material to construct a dirty bomb or radiological dispersal device, or to place stolen materials intended to harm others.

Nuclear refers to the processes that involve splitting a nucleus of an atom (Fission) or combining nuclei of atoms (Fusion) such as nuclear power plants, nuclear weapons, or nuclear explosions. Nuclear waste is actually radiological waste material from nuclear reactions.