Residents react as they watch the televised annoucement on a big video screen on Mirae Scientists Street in Pyongyang that the country has successfully tested a hydrogen bomb on September 3, 2017.
North Korea declared itself a thermonuclear power on September 3, after carrying out a sixth nuclear test more powerful than any it has previously detonated, presenting President Donald Trump with a potent challenge. / AFP PHOTO / KIM Won-Jin        (Photo credit should read KIM WON-JIN/AFP via Getty Images)