North Korea claims it carried out an underground hydrogen bomb test on Wednesday, January 6. What was the country’s intention, and how should Japan and its allies react to the situation? We talked to Professor Bruce Bennett at Pardee RAND Graduate School to find out the answers to these questions.
The pentagon and the intelligence community have cast some doubt as to whether North Korea actually detonated a thermonuclear device. What's the key evidence that they're basing this assessment on?
The whole purpose of developing a thermonuclear or so called fusion H-bomb was to have a weapon with far larger explosive power than a simple atomic bomb, a plutonium or uranium based fission weapon.
A thermonuclear weapon typically has an explosive force somewhere in the one mega ton to ten mega ton range. The device detonated recently was less than 1% of that. It was only about the size of the 1945 Hiroshima weapon. This was not a case of something that exploded with the power that a true H bomb.
There is another possibility, referred to as a boosted yield. In this case, the regular uranium or plutonium weapon explodes, and raises the rest of the contents of the weapon up to a temperature level where fusion can occur.
If you use only a little bit of the hydrogen element, you get a bit of fusion, causing parts of the uranium or plutonium to explode that normally would not have exploded. Therefore you get a higher yield overall with the weapon. That should still take you up into 50 or 100 kilotons. But the device recently detonated by North Korea was probably only in 10 to 15 kiloton range.
So, the detonated device simply does not meet the explosive power of a thermonuclear device or a device with a boosted yield. It just doesn't meet the explosive power.
Was it hydrogen at all? Unless we get some of the gases from it, we won't be able to tell for sure. It may be that it had hydrogen in it but it just didn't get hot enough to explode to cause it to go off, or it may have been that there was no hydrogen there, and Kim Jung Un was just trying to demonstrate a capability that North Korea does not yet have.
If the preliminary assessment is correct, that North Korea did not detonate a thermonuclear device, what did they detonate?
Probably a regular fission device, a regular atomic bomb like the Hiroshima bomb. That is not trivial. If this bomb were detonated in Seoul, it would kill or seriously injure 300,000 or so people. But it's not the technological accomplishment of an H bomb.
Why would they bother to test an atomic weapon when they've already done that?
The North Koreans also said the device was a miniaturized weapon; a smaller weapon, which usually refers to weapons that can be carried by a ballistic missile.
The original U.S nuclear weapons were so big that they required a huge bomber to fly them over the target. But if you can get the details of the weapon correctly, they can be small enough to fit on a ballistic missile. North Korea has been trying to get there.
The size explosion we got isn't going to tell you one way or another whether it was a miniaturized weapon but that's what they claim they were trying to get to. This may be a case where they got to something that could go on a missile and therefore that's a major accomplishment, that's an advance.
Is that where the tritium that some believe was part of the device would come into play?
Tritium would be in the boosted weapon. Tritium is usually the isotope of hydrogen that is key to a fusion reaction. Tritium could also help in the design of a miniaturized weapon. We don't know for sure that is actually what they tested, but that is what they say.
North Korea's serious problem
The North Koreans are probably aware that the U.S. and Japan, have the capability to collect forensic evidence that would disprove their claim of an H bomb, so why would they promote abroad such a blatant untruth?
We have to remember that Pyongyang’s announcement came two hours after the test. Officials in Pyongyang may not have known for sure themselves at that stage. They should have had some kind of a reading on the power of the weapon. More importantly we've got to step back and ask why in the world North Korea detonated a nuclear device at this time.
What is your best guess?
North Korea -- especially the quite young leader Kim Jung Un -- is facing a real problem. The leader of South Korea and the leader of China have done 6 summit meetings. By contrast, North Korea and China have done zero summit meetings during the time that Kim Jung Un has been the leader.
That suggests to the senior North Korean elite that China views Kim Jung Un as a weakling, as an unimportant person. North Korea has been trying very hard to get Kim Jung Un invited to Beijing. He detonates a nuclear weapon and China has told North Korea, don't do that.
I think we can conclude that China is unlikely to invite him to Beijing now. He's going to pay a price with his elite and you've got to ask why he would do that.
It seems to me that there are two possibilities. One, he may be facing internal problems, at least in his own mind, where he needed to demonstrate that he really is a powerful and advanced leader. Claiming that he's developed an H bomb suggests he wants to promote that notion that he is a capable guy because he’s achieved a big accomplishment in the scientific field. That's a possibility.
The other possibility is the Chinese told Kim that he is not invited to Beijing, and Kim got furious and decided: ‘Oh, I will show China.’ We don't know. It might not be either of those but it's quite possibly both of those. We just don't know.
Aside from a much larger explosive yield, what's the real strategic value of an H-bomb over that of a more traditional atomic weapon?
It's a matter of deterrence. If North Korea were to detonate their current size nuclear weapon on Seoul, they'd kill about 3% of the people in Seoul. If they got a true hydrogen bomb, say 5 megatons, they could destroy most of Seoul with one weapon.
It really boils down to the kind of deterrent Pyongyang want to project? South Korea could be attacked by North Korea, and though the price would be heavy, Seoul could decide to use its superior conventional forces to solve the North Korea problem once and for all.
However, if North Korea were to have a hydrogen bomb, where with one weapon it could wipe out Seoul or Busan, South Korea might be a whole lot more careful, as might the United States. Even China might be careful.
At the moment, China has been pushing Vietnam and the Philippines around, treating those two countries as weakling states. Doesn't China’s reluctance to really pressure North Korea teach a lesson to Vietnam and the Philippines: even a single nuclear weapon would compel China to give them respect.
It's also a matter of international power and prestige, and domestic power and prestige within the government. All of these are factors in Pyongyang’s decision to upgrade its military capabilities.
The price Kim Jung Un has to pay
What policy options does the U.S and Japan have?
We've used most of the economic sanctions available, though there are more things we could try to lock North Korea out of the international finance system.
We did years ago with the Banco Delta Asia actions. We could do something a little bit more extreme, but I think what we miss is the fact that the purpose of this test wasn't about economics. It wasn't to force countries to trade with North Korea, it was heavily about internal politics.
If that's the case, why aren't we responding with an internal political response? North Korea did not like the political broadcasts that South Korea used last August. South Korea is about to start them again. North Korea was very upset about those broadcasts.
There are other things we can do to influence the political situation inside North Korea. We can tell North Korea, look now that you've done this ... we're going to throw a whole bunch of leaflets at every one of your nuclear facilities.
The leaflets would seek North Korean defectors from the country’s nuclear program because we want the intelligence we would gain. The leaflets would try to convince them that they could do physics research at South Korean universities, or work in a South Korean nuclear plant and not die of radiation.
If one person defected after that, Kim Jung Un would suffer a loss of face. Now he would have to take all kinds of action to prevent that from happening. That's going to be a price that he would pay and a risk he would pay that somebody would get away. He won't be able to send his scientists to Iran and other places as he's been because they might defect, in the process.
We should be evolving toward that kind of political response. We know that North Korean soldiers face starvation in the military. They don't get fed very well, why aren't we saying that? We should be saying why is it that Kim Jung Un has reported ... 5 Billion Dollars in family bank accounts overseas but he won't pay the couple hundred million a year that he has to, to feed his military.