SEOUL–Within hours of North Korea causing a global news flurry Wednesday with its announcement that it had detonated its first hydrogen bomb, a consensus emerged among experts that the country was probably bluffing and had tested a much less powerful atomic device.
But even if Pyongyang didn’t detonate a hydrogen bomb, a weapon potentially thousands of times more powerful than the atomic bomb that leveled Hiroshima, its fourth nuclear weapons test in a decade could still represent a significant advance in its ability to inflict mass destruction, analysts told Asia Times.
While the exact yield of the explosion at the Punggye-ri test site yesterday remained unclear, seismic activity recorded afterward quickly led observers to conclude it was too small for a weapon based on nuclear fusion.
They pointed to the likelihood of a nuclear fission device, the kind of weapon used in previous detonations, possibly enhanced with fusion material to create a bigger blast. A clearer picture of the size and nature of the device could depend on analyzing resulting radioactivity, for which purpose the US and Japan dispatched military aircraft.
“It is too small to be a staged thermonuclear weapon, but it might be boosted using D-T gas. D and T are isotopes of hydrogen,” said Jerry Lewis, the founder of the Arms Control Wonk website. “Hence, ‘hydrogen bomb.’”
This technology could have contributed to the blast being moderately more powerful than Pyongyang’s last test in 2013. Loose estimates of the yield of the latest detonation have ranged from 3 to 9 kilotons. “Little Boy,” the bomb dropped on Hiroshima, produced a yield of 15 kilotons.
Significantly, however, the boosting technology could also aid Pyongyang in perfecting the ability to mount a nuclear device on a missile, said Carl Robichaud of the Carnegie Corporation of New York.
“If North Korea masters fission boosting, it will allow for smaller warheads. Miniaturization is key if you want to put a warhead on a long-range missile,” Robichaud said. “A focus on this test as a failed or fake H-bomb may be missing the larger story. North Korea may be making important progress in its nuclear arsenal, progress that is less about yield and more about deployability.”
Kelsey Davenport, director for nonproliferation policy at the Washington, D.C.-based Arms Control Association, said Wednesday’s test would inevitably add to North Korea’s knowledge of nuclear weapons.
“Even if the test was not a hydrogen bomb, the test will still advance North Korea’s nuclear program. There are a lot of unknowns about the type of device — North Korea could have been testing a boosted fission device, which is a more efficient fission design, or a miniaturized device,” she said. “Regardless of the type, Pyongyang will be able to gather information about warhead design and operation that could help it qualitatively improve its nuclear arsenal.”
Whether or when North Korea could gain the ability to mount a nuclear warhead on a missile has long been a concern of the international community, particularly in the US and South Korea. In its announcement of the latest detonation, North Korea said it had tested a miniaturized device, a claim that was impossible to verify.
In October 2014, Gen. Curtis Scaparrotti, the commander of US Forces Korea, said he believed North Korea did not have the technology but that it was within reach of the regime. US military officials have said they believe North Korea’s longest-range missiles are capable of striking the US West Coast.
Reflecting widespread condemnation of North Korea’s latest actions, the UN Security Council gathered in a special session on Wednesday. Calling the weapons test a “clear threat to international peace and security,” it vowed to take action against the country, without specifying what kind.
John Power is a journalist who has reported on North and South Korea since 2010. His work has appeared in outlets including The Daily Mail, The Christian Science Monitor, Mashable, NK News, Asian Geographic, The Diplomat, The Korea Herald and Narratively, among others.