Sanctions stay till North Korea takes 'irreversible' steps: South Korea, U.S. defense chiefs

SEOUL (Reuters) - United Nations sanctions against North Korea should remain in place until North Korea takes concrete, irreversible steps toward denuclearization, the defense chiefs of South Korea and the United States said on Thursday. U.S. Defence Secretary Jim Mattis and his counterpart Song Young-moo also agreed to explore additional confidence-building measures while North Korea continues dialogue "in good faith," according to a joint statement released by Seoul's defense ministry after their talks in Seoul. (Reporting by Hyonhee Shin and Christine Kim)