Evidence that terrorists are actively seeking nuclear weapons and the materials needed to make them, and that some nuclear stockpiles around the world remain dangerously vulnerable to potential theft and transfer to terrorist groups, continued to accumulate in the past year. A comprehensive strategy for preventing nuclear terrorism would include many strands, from offensive action against terrorists with global reach to measures to stop nuclear smuggling. But the most crucial element of such a strategy is to lock down every nuclear weapon and every kilogram of potential nuclear bomb material everywhere. Because nuclear weapons and their essential ingredients do not occur in nature and are too difficult for terrorists to plausibly produce on their own, if these stockpiles can be kept out of terrorist hands, nuclear terrorism can be reliably prevented.
Bunn, Matthew, and Anthony Wier. "Securing the Bomb 2005: The New Global Imperatives." May 2005.