Last Friday, the U.N. Security Council adopted a resolution calling on nations to maintain their moratoria on nuclear weapons testing pending ratification of the Comprehensive Nuclear-Test-Ban Treaty. Leading up to the resolution, current and former policymakers reflected on the 20-year-old treaty’s prospects, including Energy Secretary Ernest Moniz, who referred to ratification of the treaty as “unfinished business,” and former senator Jon Kyl (R-AZ), who argued that the U.S. should never ratify the treaty.