In 1969, a year after he was elected U.S. president, Richard Nixon renounced the use of any form of deadly biological weapons that either kill or incapacitate." Nixon's declaration is one of the few cheerful spots in "The Living Weapon," a PBS program that [aired] Feb. 5. The U.S. got into the germ-warfare business in 1942 at the request of Britain, which feared that Adolf Hitler was cooking up world-class pestilence in his labs. As it turns out, Hitler early on ordered that "there was to be no offensive biological weapons research." His benevolence may have been the result of having been gassed in World War I, the show suggests. The U.S. program, headquartered at Fort Detrick, Maryland, ... used human subjects, though many were volunteers. Most were Seventh-Day Adventists, who as conscientious objectors refused to bear arms. About 2,200 of them agreed to inhale various non-lethal agents that made them, as one expert says, "pig sick." The idea behind the experiment, the show says, was that a sick soldier in the field creates a much greater strain on an army than a dead one. The government also bombarded several U.S. cities with simulants -- non-infectious bacteria -- to assess how biological agents spread. Targets in that super-secret program included San Francisco, St. Louis and Minneapolis. The end to the U.S. development program may have been partly the result of a 1969 Utah incident in which an "errant cloud" of nerve gas was held responsible for killing some 6,000 sheep.