One-liner: Explores attempts by terrorists to acquire nuclear materials and fabricate nuclear systems and suggests that strict controls on nuclear weapons, materials, and expertise will reduce opportunities for terrorists to acquire them. 450-character abstract: Revelations about A.Q. Khan's global nuclear marketing efforts and Osama bin Laden's contact with Pakistani nuclear scientists have raised concerns about terrorist acquisition of a nuclear or radiological weapons capability. Such a capability would pose a grave danger to U.S. national security and to the security of the international system of nation-states. This study suggests that strict controls on nuclear weapons, materials, and expertise will reduce opportunities for terrorists to acquire these resources.