North Korea detonated a thermonuclear device Sunday in its sixth and most powerful nuclear test to date, which it called a "perfect success" as its neighbors condemned it. Though the strength of the blast is undetermined, the artificial earthquake it caused was several times stronger than tremors generated by previous tests. It reportedly shook buildings in China and Russia. The test was carried out at 12:29pm local time at the Punggye-ri site where North Korea has conducted nearly all of its nuclear tests. Seoul put the magnitude at 5.7, while the USGS said it was 6.3. North Korea's state-run television reported Sunday that Kim Jong Un attended a meeting of the ruling party's presidium and signed the go-ahead order. Earlier in the day, the party's newspaper printed photos of Kim examining what it said was a nuclear warhead being fitted onto the nose of an ICBM.
North Korea in July test-launched two ICBMs believed to be capable of reaching the mainland US, reports the AP; this is the North's first nuclear test since President Trump assumed office. The North claimed the device was a thermonuclear weapon—commonly called an H-bomb. That could be hard to independently confirm. It said the underground test site did not leak radioactive materials, which would make such a determination even harder. The North claims the device was made domestically and has explosive power that can range from tens to hundreds of kilotons. Outside experts suggested the yield might be in that ballpark, though closer to the lower range. The bomb dropped on Hiroshima had a 15-kiloton yield. Kim, according to the state-run KCNA, claimed all components of the device were domestically produced, which he said means the North can make "as many as it wants." (Read more North Korea stories.)