A closer look at the test
North Korea’s claim that it had tested a hydrogen bomb alarmed Pyongyang’s Asian neighbors — and the rest of the world. A look at what’s behind this new North Korean claim — if it’s true:
Q: Is this a big deal? We already knew they had atomic bombs.
A: It’s a big deal because a hydrogen, or thermonuclear, bomb is much, much more powerful. The atomic bomb that the U.S. dropped on the Japanese city of Hiroshima in 1945 had a yield of 15 kilotons, while the one dropped on Nagasaki had a yield of 20 kilotons. The hydrogen bomb that the U.S. tested at Bikini Atoll in 1954 had a yield of 15 megatons — making it more than 1,000 times as powerful as the Hiroshima bomb.
Here’s how Kim Du-Yeon of the Carnegie Endowment for International Peace explained it: “An atomic bomb uses fission and an H-bomb uses fusion. A [thermonuclear bomb] has an exponentially greater yield [thousands of times more powerful]. It includes an atomic bomb inside its core that acts as a trigger.”
Q: Was this a surprise?
A: Not really. In December, Kim Jong Un said his country was “a powerful nuclear weapons state ready to detonate self-reliant A-bomb and H-bomb to reliably defend its sovereignty and the dignity of the nation.” Before that, the North Korean ambassador to London had said in a speech that North Korea had weapons that were “ten times as powerful” as the nuclear devices it had previously detonated.
Q: How scary is this?
A: There’s still a considerable degree of skepticism about whether this really was a hydrogen bomb that was tested today. Jeffrey Lewis, a nuclear expert at the Middlebury Institute of International Studies, said after Kim’s claim in December: “Building a staged thermonuclear weapon — one in which the radiation from a fission primary compresses a secondary stage of thermonuclear fuel — seems to be a stretch for the North Koreans. That is the sort of device one normally thinks about when someone says ‘H-bomb.’ Thermonuclear weapons are tricky; making one work requires a bit of test experience. While the North Koreans conducted an unambiguously successful nuclear test in 2013, the 2006 and 2009 tests were less so.
Q: Why now?
A: It’s Kim Jong Un’s birthday on Friday — probably his 33rd, although it could be his 32nd, such is the paucity of our knowledge about the “Great Successor” — so the launch could be an early gift for him. The leaders’ birthdays are always celebrated with a lot of fanfare in North Korea.
More likely this is all about preparing for the much-awaited Seventh Congress of the Korean Workers’ Party in May this year, the first in 36 years.
Q: So what happens now?
A: Regardless of whether the explosion was atomic or thermonuclear, it was a brazen provocation and a clear defiance of international treaties. So get ready for lots of international condemnation and some stern words at the United Nations. Already North Korea’s neighbors — South Korea, Japan and China — have sternly criticized the test, and the United States is getting ready to do so, once it’s confirmed. The United Nations already is planning additional sanctions.