Stopping the proliferation of nuclear weapons and ballistic missiles remains a primary objective of U.S. foreign policy. However, most experts and policy makers realize that non-proliferation efforts will not stop every country from succeeding in acquiring these capabilities. Non-nuclear weapon states largely pursue these capabilities to either address security concerns or increase their influence in a given region. To counter this emerging threat the U.S. continues its development of a ballistic missile defense system. Given the unparallel military force of the U.S., it is hard to image a nuclear attack on the U.S. or an allied territory that does not result in self-destruction for a regional adversary; however, a policy based on unanticipated use clearly is unacceptable. The U.S. must be prepared to deter an adversary from launching a nuclear strike as a first strike and avoid inciting a last resort response during an escalating crisis or conflict. However, accomplishing these goals is more difficult than it seems due to the high level of interests involved and will take more than an operational missile defense system.