The Department of Homeland Security is dismantling a next-generation biological attack warning system in New York City subways because of technical problems, U.S. officials said. Robert Hooks, a deputy assistant secretary, said the department no longer believes it is necessary to expand the pilot program, as he told Congress in July, because of resource and technology limits. Hooks said a long-planned alternative sensor system, set for initial deployment late next year, also will not be available nationwide until 2012, to allow for more testing. The deactivation of the pilot program in late March marks a setback in U.S. efforts to...