World leaders slammed North Korea on Wednesday for carrying out a fourth nuclear test, an explosion that Pyongyang claimed was a powerful hydrogen bomb but whose strength was strongly questioned by international experts and American officials. White House spokesman Josh Earnest said initial data from various monitoring sources were “not consistent with North Korean claims of a successful hydrogen bomb test.”
Nuclear monitors also said the magnitude of the blast suggested an atomic explosion rather than one produced by an exponentially more powerful hydrogen device — potentially more than 1,000 times more destructive than the bomb dropped on the Japanese city of Hiroshima near the end of World War II.
Despite the widespread skepticism about the North’s assertion, data from the blast will be carefully scrutinized for any hints of technological advances in its nuclear program. Even incremental progress would demonstrate that the North has been able to develop its expertise despite international sanctions and other pressures.
North Korea sent political shock waves around the world on January 6 when it claimed to have carried out a successful test of a hydrogen bomb, which, if true, would be a substantially more powerful and sophisticated class of weaponry than the country’s previous efforts. The underground test generated a magnitude 5.1 earthquake, according to the U.S. Geological Survey. Verifying the country’s boast will be tricky, however. Here’s what experts have sussed out so far and which questions are still up in the air.
Nuclear bombs cause much bigger booms than their nonnuclear counterparts. A 2013 nuclear test in North Koreareleased energy equivalent to the detonation of around 6 to 9 kilotons of TNT. For comparison, the 1917 Halifax Explosion in Nova Scotia, the largest artificial explosion until the advent of nuclear weapons, only clocked in at the equivalent of about 2.9 kilotons of TNT.
While North Korea declares that it tested a hydrogen bomb, a lot of evidence doesn’t fit that claim, experts say. H-bombs, also called thermonuclear bombs, are much more powerful than the plutonium-powered weaponry that North Korea has tested in the past. The country’s early devices broke apart plutonium atoms in a process called fission, releasing large amounts of energy. The test’s relatively puny size suggests that either the North Korean government exaggerated its bomb’s capabilities, or the bomb tore itself apart without successfully igniting its secondary fusion stage, nuclear experts contend.
According to Dill, the December 2015 test video was edited to appear as though the KN-11 ballistic missile launch was successful. However, North Korean video editors left in an extra two frames of video that should have been cut. They indicate the missile exploded, she says. Dill told PopMech, "The missile successfully ejects, which would mark an improvement in testing if reports about a failed ejection test in November are accurate. However, the missile then appears to explode, and we conclude that the failure likely occurred at ignition."
Dill and her colleagues compared the launch footage to archival footage of the Soviet Union's R-27 submarine-launched ballistic missile. "Compared to Soviet-era test footage of an R-27 launch, on which the KN-11 is based, the failure seems clear," Dill said. KN-11 is the designation for a new ballistic missile being developed on North Korea's east coast, near the town of Sinpo. The missile is expected to be carried by the new Gorae-class ballistic missile submarine and will likely be fitted with a nuclear warhead.
North Korea has broadcast a new video purportedly showing Saturday’s long-range rocket launch, which sent a satellite into orbit.
In the video released Thursday by the regime’s state broadcaster, titled ‘The Launching of the Earth Observation Satellite Kwangmyongsong-4,’ the rocket is seen shooting off from a gantry. It then cuts away to footage of the North Korean leader Kim Jong Un speaking to officers and traveling on a plane.
U.S. officials say the satellite is now “tumbling in orbit” about 300 miles above earth. Its launch has been strongly condemned by the international community.
North Korea fired several short-range projectiles into the sea off its east coast, Seoul said Thursday, hours after the U.N. Security Council adopted tough new sanctions against Pyongyang's nuclear and ballistic missile programs. South Korea's defense ministry said it was still trying to determine the number and nature of the projectiles, which it said were fired into the Sea of Japan at 10 a.m. local time (1:00 UTC).
The move could be a response to the Security Council's unanimous approval Wednesday of sanctions against Pyongyang for its recent nuclear and long-range rocket launch.