Scott D. Sagan notes that the question of why states seek to build nuclear weapons has scarcely been examined, although it is crucial to efforts at preventing proliferation. He challenges the traditional realist assumption, accepted uncritically by many scholars and policymakers, that states seek to acquire or develop nuclear weapons primarily for military and strategic reasons. Sagan examines alternate explanations for the demand for nuclear weapons.

Revised and updated versions of this article also appear as "The Causes of Nuclear Proliferation," Current History (April 1997), pp. 151-156; as "Why Do States Build Nuclear Weapons?" in Victor Utgoff, ed., The Coming Crisis: Nuclear Proliferation, U.S. Interests, and World Order (MIT Press, 1999), p. 17-50; and as "Why Do States Build Nuclear Weapons? Three Models in Search of a Bomb," in New Global Dangers: Changing Dimensions of International Security (International Security Reader, July 2004).