As the United States plays a greater role in the 21st Century as global peacekeeper and international defender of human rights and democratic principles, there is an increasing likelihood that it will become the focus of acts of terrorism. Such acts of terrorism--sometimes described as ''asymmetric''--could involve the threat or use of weapons of mass destruction (WMD), particularly those considered unconventional, which include ones designed to release chemical or biological agents. In fact, biological agents are of great concern because, as noted by D.A. Henderson of the Center for Civilian Biodefense Studies at Johns Hopkins University in Baltimore, MD, ''... with shortages of hospital space, vaccines, antibiotics, there would be chaos.'...