In the past three decades, North Korea has gone from threatening to pursue nuclear weapons development to allegedly conducting a successful hydrogen nuclear test.
원문출처 : http://edition.cnn.com/2016/01/05/asia/north-korea-nuclear-timeline/index.html?eref=edition
원문출처 : http://edition.cnn.com/2016/01/05/asia/north-korea-nuclear-timeline/index.html?eref=edition