North Korea claimed this morning to have successfully tested a miniaturized hydrogen bomb. The first thing to keep in mind is that claims by Kim Jong-un’s repressive regime should not be taken at face value. As arms control expert Joshua Pollack wrote after a previous North Korean claim several years ago, “obviously this is balderdash, but what kind of balderdash is it?”
Something caused a 5.1 magnitude earthquake near the Punggye-ri site where North Korea has tested weapons in the past, and if the test really happened, it wouldn’t be entirely without warning. Last month, the North Korea analysis site 38 North posted satellite imagery that appeared to show the construction of a new tunnel for testing at Punggye-ri. Kim also said last month that North Korea had become a "powerful nuclear weapons state ready to detonate a self-reliant A-bomb and H-bomb to reliably defend its sovereignty and the dignity of the nation," but experts at the time mostly dismissed this as a rhetorical flourish.
The H-bomb claim is still being met with skepticism on Wednesday. While the tremor caused by the blast was felt as far away as northeast China, a quake caused by a hydrogen bomb would have been much larger. A Rand Corp. analyst suggested to the BBC that the bomb was likely in the 10-15 kiloton range, only slightly larger than North Korea’s last test in 2013 and around the size of the atomic bomb dropped by the U.S. on Hiroshima. Other estimates put it in the 6-7 kiloton range.
A true hydrogen bomb, which draws its power from nuclear fusion rather than fission, can be thousands of times more powerful. As Winston Churchill famously put it, it’s as far from the A-bomb as the “atomic bomb itself from the bow and arrow.” The U.S. first tested a fusion bomb in 1952 but one has thankfully never been used in war.
So a true hydrogen bomb is unlikely. There is also an intermediate step between the atomic and hydrogen bomb, in which a small amount of fusion fuel is used to boost the power of a fusion reaction. As nuclear expert Joe Cirincione told Reuters, if North Korea mixed a hydrogen isotope into a normal bomb, “they could claim it is a hydrogen bomb. But it is not a true fusion bomb capable of the massive multi-megaton yields these bombs produce." It may be weeks before the U.S. and other powers can determine what kind of test took place. The claim of miniaturization—important in terms of North Korea’s quest to develop a weapon it can launch on a missile—will be even more difficult to verify.
Even if North Korea doesn’t have an H-bomb, the test suggests that its nuclear program is continuing to develop in spite of the international sanctions put in place after its first atomic bomb test in 2006. Eccentric and tyrannical as they may be, North Korea’s leaders probably aren’t suicidal enough to actually use a nuclear weapon, but that’s not particularly reassuring for South Korea or Japan. And the more Kim’s program develops, the higher the risk of an accident—or of the regime giving nuclear material to others who will actually use it.
One thing that the test definitely does is ensure North Korea’s continued relevance on the world stage, particularly in the United States, where it has detonated in the middle of a campaign season as perfect fodder for candidates to decry President Obama’s “failed leadership” and ramp up their attacks on the recently concluded nuclear deal with Iran. But given that threats only play to the regime’s advantage and that a government that doesn’t particularly care about the welfare of its people its perfectly willing to weather additional sanctions, it’s not clear just how much leverage the U.S. has.
The test is also, as journalist and longtime North Korea watcher Mike Chinoy puts it, a “slap in the face to China,” which has been urging its erstwhile ally to return to international denuclearization talks. China–North Korea relations have been frostier of late as China has sought to improve ties with South Korea, though the two countries played up their relationship at a military parade in Pyongyang last fall. The Chinese foreign ministry put out a strong statement in opposition to the tests on Wednesday and urged North Korea to return to talks, but it’s unlikely the situation will escalate much beyond that.
While North Korea is an increasing irritant for China, Beijing is thought to have calculated that a neighbor led by a sadistic nuclear-armed lunatic is still less dangerous than a collapsed regime sending thousands of traumatized refugees to its border. Though they’re less likely to admit it, South Korean leaders probably feel the same. That calculus won’t significantly change, even if Kim has gotten his hands on a somewhat more powerful weapon.