North Korea claimed to have tested its miniaturised thermonuclear bomb on January 6 , 2016 . North Korea 's first three nuclear tests ( 2006 , 2009 and 2013 ) were relatively low yield and do not appear to have been of a thermonuclear weapon design . In 2013 , the South Korean Defense Ministry has speculated that North Korea may be trying to develop a " hydrogen bomb " and such a device may be North Korea 's next weapons test . In January 2016 , North Korea claimed to have successfully tested a hydrogen bomb , though only a magnitude 5.1 seismic event was detected at the time of the test , a similar magnitude to the 2013 test of a 6 – 9 kt atomic bomb . These seismic recordings have scientists worldwide doubting North Korea 's claim that a hydrogen bomb was tested and suggest it was a non-fusion nuclear test . On September 9 , 2016 , North Korea conducted their fifth nuclear test which yielded between 10 and 30 kilotons
fifth nuclear test
September 2016 North Korean nuclear test
History of the Teller–Ulam design