Exclusive: North Korea may be 'significantly' upping nuclear bomb output - report

By David Brunnstrom and Jonathan Landay WASHINGTON (Reuters) - North Korea may be significantly expanding its nuclear weapons production and could have added six or more weapons to its stockpile in the last 18 months, a U.S. research institute said on Tuesday. The Washington-based Institute for Science and International Security (ISIS) estimated last year that North Korea had 10 to 16 nuclear weapons at the end of 2014. It based that conclusion on an analysis of the country's production of weapo