North Korea tested its fourth nuclear device at Sungjibaegam, Punggye-ri, in North Hamgyong Province, in the northeastern part of the country. The government claims the test was a “miniaturized H-bomb.” There are doubts that it was a hydrogen bomb, however, and the explosion is thought to have been on the order of ten ktons, likely due to fission, perhaps followed by a “boosted explosion,” where tritium (an isotope of hydrogen) undergoes partial fusion.
