More than 500,000 troops are expected to receive the smallpox vaccination as America braces for war in Iraq. Many already have begun the process. They are not alone. From the Office of Homeland Security to city councils across the country, folks are revamping contingency plans to keep pace with possible threats against the country. For the first time in recent history, U.S. physicians have inherited the daunting task of recognizing and containing a biological attack on U.S. soil.