The new START treaty that would cut the number of U.S. and Russian nuclear weapons could also prompt the United States to trim the bomber leg of its nuclear force. Limits that reduce the number of deployed "launchers" to 700 could encourage U.S. nuclear policy makers to rely more on land-based and sea-based ballistic missiles and less on B-2 and B-52 bombers, said Tom Collina, research director at the Arms Control Association. "The bomber leg of the triad is not what you think about when you think about survivability and quick response," he said. At present, the United States has...