Witnesses: Frank J. Cilluffo, senior policy analyst, Center for Straategic & International Studies (CSIS), Wash., DC; Donald A. Henderson, MD, MPH, dir., Center for Civilian Biodefense Studies, Johns Hopkins Univ.; David L. Heymann, MD, exec. dir., Communicable Diseases, World Health Organization (WHO), Geneva, Switzerland; Dr. Fred C. Ikle, distinguished scholar, CSIS; Sam Nunn, co-chair & ceo, Nuclear Threat Initiative, Wash., DC; & R. James Woolsey, former Dir. of Central Intelligence (CIA), & partner, Shea & Gardner, Wash., DC.