The Comprehensive Test Ban Treaty signed today at the United Nations bans nuclear tests in the atmosphere and underground, and it sets up a monitoring system to spot violations. There are flaws, however. A provision in the treaty requires legislative ratification in 44 potential nuclear states. India has refused to sign until all countries with nuclear weapons devise a timetable for destroying all their weapons. NPR's Ted Clark reports that despite those flaws, the treaty is a political consensus that will apply pressure for all countries to comply.