STAFF SGT. Kevin Buckalew, chemical warfare instructor for Headquarter Company, 16th Signal Battalion, Fort Hood, Texas, observes Sergeant Polk and Sergeant Smith of B-Company, 16th Signal Battalion as they use a M256A1 Chemical Agent Detection Kit during chemical warfare training at McGregor Range, New Mexico prior to start of Roving Sands '96, the US military's largest annual joint air defense training exercise