North Korea conducted its sixth and most powerful nuclear test on Sunday, which it said was a successful detonation of an advanced hydrogen bomb, technically known as a two-stage thermonuclear device.
All of North Korea’s six nuclear tests including the one on Sunday have taken place at its underground testing site in Punggye-ri, deep in mountainous terrain, and it is hard to independently verify the claims.
But experts who studied the impact of the earthquake caused by the explosion - measured by the U.S. Geological Survey at magnitude 6.3 - said there was enough strong evidence to suggest the reclusive state has either developed a hydrogen bomb or was getting very close.
The detonation produced 10 times more power than the fifth nuclear test a year ago, South Korean and Japanese officials said. NORSAR, a Norwegian earthquake monitoring agency, estimated the yield at 120 kilotons, significantly above the 15 kiloton “Little Boy” bomb dropped on Hiroshima and the 20 kiloton “Fat Man” dropped on Nagasaki at the end of World War Two.
“That scale is to the level where anyone can say (it is) a hydrogen bomb test,” said Kune Y. Suh, a nuclear engineering professor at Seoul National University.
“North Korea has effectively established itself as a nuclear state. This is not just a game changer, it’s a game over,” Suh said.
Lassina Zerbo, executive secretary of nuclear test ban watchdog CTBTO, said: “The physics of the event that we’re talking about today seems to indicate a much larger event than the one from 2016 and before.”
North Korea claims its intercontinental ballistic missiles (ICBMs) tested twice in July can reach large parts of the mainland United States.
