Pacific Rim leaders rushed to condemn Pyongyang as the isolated nation boasted in an excited televised address that the explosive device was a hydrogen bomb developed for its line of intercontinental ballistic missiles.
The U.S. Geological Survey detected the test through seismic activity recorded at around 12:30 p.m. local time. The large quake was described as an “explosion.” A second tremor, clocking in at magnitude 4.1, was recorded minutes later and at the same location. Seismologists categorized it as a “collapse.”
“It is absolutely unacceptable if North Korea did force another nuclear test, and we must protest strongly,” Prime Minister Shinzo Abe said sternly.
North Korea’s latest test is believed to have greatly surpassed its last detonation nearly a year ago on Sept. 9, which packed 15 to 25 kilotons — similar to the atomic bomb dropped on Nagasaki during World War II. The rumbling was felt along China’s border to North Korea and up the Russian coast.
It interrupted brunch for Michael Spavor, director of the Kaektu Cultural Exchange with North Korea, in a neighboring Chinese city.
“I was eating brunch just over the border here in Yanji when we felt the whole building shake,” Spavor told Reuters. “It lasted for about five seconds. The city air raid sirens started going off.”
The U.S. State Department had no immediate reaction.