Many policymakers and scholars contend that nuclear weapons remain inaccessible to terrorists, and that nuclear means are inconsistent with or disproportionate to their goals. Nevertheless, the historical pattern of nuclear proliferation suggests a trend toward nonstate actor acquisition, a notion supported by recent developments in the black market. Additional evidence suggests that some specific groups have expressed an interest in nuclear weapons. This thesis proposes that there is a terrorist demand for nuclear weapons. Further, its findings suggest that the possibility of terrorist acquisition has grown; and that these nonstate adversaries will enjoy significant advantage over states during nuclear crisis. Terrorists, like states, pursue political objectives and have similar concerns regarding power and security. Lacking state resources, terrorists employ instrumental targeting in pursuit of those objectives, while remaining relatively invulnerable to retaliation. This dynamic will encourage terrorists to acquire and exploit nuclear potential, thereby overturning traditional theories of deterrence. Wishful thinking about nuclear terrorism has discouraged thoughtful analysis of this dilemma. The prospect is sufficiently dire, that a preventive campaign must be launched to stop terrorist acquisition of nuclear capabilities. Policymakers must also prepare for the possible failure of preventive efforts, and search for options that may mitigate nuclear terrorism.