"Smallpox virus, which is among the most dangerous organisms that might be used by bioterrorists, is not widely available. The international black market trade in weapons of mass destruction is probably the only means of acquiring the virus. Thus, only a terrorist supported by the resources of a rogue state would be able to procure and deploy smallpox. An attack using the virus would involve relatively sophisticated strategies and would deliberately seek to sow public panic, disrupt and discredit official institutions, and shake public confidence in government. The following scenario is intended to provoke thought and dialogue that might illuminate the uncertainties and challenges of bioterrorism and stimulate review of institutional capacities for rapid communication and coordinated action in the wake of an attack."
Centers for Disease Control: http://www.cdc.gov/
Emerging Infectious Diseases (July-August 1997), v.5 no.4, p. 540-546