A new threat is stalking nations, as terrorist organizations and rogue states alike appear intent on acquiring and using the poor man's nuclear weapon: biological agents such as anthrax, smallpox, and plague. Attacks against Americans during the past dozen years may be an indication of more worrisome events to come. U.S. military forces in Japan were attacked in April of 1990 with botulinum toxin by the Aum Shinrikyo cult. Hundreds in Oregon were...