In a surprise announcement, North Korea’s state-run television news claimed Wednesday that the government had tested a hydrogen bomb in an area of the country where there have been three nuclear tests since 2006. Seismographs around the world registered an earthquake at 5.1 on the Richter scale in the area from an apparently manmade explosion.
If North Korea’s declaration proves accurate, the test would represent a substantial and dangerous advance in its efforts to become a nuclear weapons player. But not long after the test, international nuclear experts began to express doubt that the device was an actual hydrogen bomb. Some analysts speculated that it may have been a boosted fission weapon, with tritium and deuterium gas added to give it more power, but still less powerful and complex than a hydrogen bomb.
Officials in the United States, neighboring South Korea, China, Japan, and Russia, as well as across Europe, strongly condemned North Korea’s actions. The U.N. Security Council called an emergency meeting to condemn the test, which violates U.N. resolutions.
Two analysts from the Belfer Center for Science and International Affairs at Harvard Kennedy School, Matthew Bunn, co-principal investigator of the Project on Managing the Atom, and Gary Samore, the center’s executive director for research, spoke with the Gazette about North Korea’s nuclear program and what the latest test means for relations between the government of leader Kim Jong-un and other nations, and how the blast may affect global efforts to limit nuclear weapons.
GAZETTE: First, there is some doubt and debate about North Korea’s claim that a hydrogen bomb was detonated. What do you suspect it was?
BUNN: All we know so far is how much of a seismic signal it sent, and that tells you roughly how big the bomb was. And the seismic magnitude is the same as it was in 2013, so if they have a different kind of bomb, it apparently didn’t create a bigger, more powerful bomb — yet.
GAZETTE: Does a 5.1 reading eliminate the possibility that it could be a hydrogen bomb?
BUNN: It doesn’t eliminate it, but it makes it quite unlikely. The advantage of a hydrogen bomb is you can make a much bigger bomb. Countries don’t generally make teeny, tiny hydrogen bombs when they’re early in their nuclear development, as North Korea is. That’s all we know — how big the explosion was, roughly. Everything else is speculation. Often the North Koreans exaggerate what they’ve accomplished, but have some small grain of truth in their statements. So one possibility that’s being speculated about that I think is at least plausible is that this was a boosted fission weapon. What that means is that there is a little bit of fusion taking place, so you can sort of call it a hydrogen bomb. That’s what I mean by the grain of truth.
In a normal fission bomb, you have a core of plutonium or highly enriched uranium, which is crushed by explosives, and then the atoms split, releasing the nuclear energy in the bomb. You can make that core a hollow ball and you put some tritium and deuterium, which are kinds of hydrogen, in it. (Normally, hydrogen just has a proton as its whole nucleus with an electron zipping around outside. Deuterium has two things in the nucleus, a proton and a neutron. Tritium has three, a proton and two neutrons.) So if you put some tritium and deuterium in that hollow core, then when the fission reaction happens and you get these incredible temperatures and pressures — more than the center of the sun — that causes the tritium and the deuterium to fuse, and you get some fusion reaction. But more importantly, that releases a bunch of neutrons which then make the plutonium or the uranium fission more efficient, and so you get a larger bang out of the same amount of plutonium or highly enriched uranium. I think it’s at least plausible that what they were doing in this test was a boosted test. However, they didn’t get any bigger bang out of it than they did in 2013. So if it is boosted, that doesn’t seem to have done them a lot of good.
GAZETTE: Is there a way the U.S. or others can verify what it is? And how long might that process take?
BUNN: If it leaked a lot of gases and you managed to pick up those gases [through monitoring instruments], then you might be able to learn something. But the North Koreans are good enough at this now that I don’t expect there’ll be any gases to be seen. So the short answer is no, not really. There’s not a lot of information available, so what you know is the shockwave that went out through the Earth from that explosion, and that’s about all you know.
I’m sure the Chinese will be making statements — they have good contacts with North Korea. The North Koreans will be making statements. There will be a lot of statement-type “evidence” that people will be drawing on and trying to parse and figure out. But in terms of direct scientific knowledge, no, there’s not a lot we can do.
GAZETTE: This isn’t North Korea’s first test. What’s the significance if it is a hydrogen bomb, and was it a surprise to experts?
BUNN: If it was a boosted-fission weapon, it would be an advance in their nuclear weapon technology. If it was a real hydrogen bomb, which I doubt, it would be a dramatic step forward in their nuclear weapon technology and would offer the potential for either nuclear weapons of enormous yield or nuclear weapons of substantial yield that are quite miniaturized, although both of those would potentially require more work. So we just don’t know its technical significance until we know more about what it actually was.
It was certainly no surprise that they conducted a fourth nuclear test. They had asserted back in December that they had mastered hydrogen bomb technology, so in a certain sense it’s no surprise that they asserted that it was a hydrogen bomb test. But it would certainly be a surprise if it actually was a hydrogen bomb test. Making a hydrogen bomb is very technically challenging, and it would be a big surprise to me if North Korea had managed to do it. Making a boosted-fission weapon is much, much less challenging, and would be much, much less surprising.
GAZETTE: How sophisticated is their program and what kind of timetable or runway does North Korea appear to be on in its nuclear program?
BUNN: The debate that is still underway — and it’s a debate based on substantial speculation — is: Have they managed to make a bomb that is, a), reliable, and b), small enough to put on the front of a ballistic missile? There are some people who say they haven’t, and some people who say they have. I would argue we don’t know the answer. But we should assume, on the basis of conservative defense planning, that they can probably do that. So we should assume that they either have or will soon have ballistic missiles that could deliver a nuclear weapon.
They are working on making longer-range ballistic missiles. So far, their technology in both departments seems to be modest … but the level of information that we have available is really quite modest. On the missiles, the situation is better because they launch up into space, and you can watch them, and you look at pieces as they fall down in the ocean, and you manage to recover them. But for things that go bang in a hole in the ground in a country you can’t go to, that’s a tough problem.
GAZETTE: What is the end game for North Korea in developing a nuclear program?
BUNN: That is a question the U.S. government really wishes it knew. They have asserted for decades that the United States has a hostile policy and threatens them, and therefore they need a nuclear deterrent to protect their regime. I think the view of most U.S. analysts is that they do see it as a key element of regime survival. They know that in a perfect world the United States would prefer that the government of North Korea be different than it is, and they have seen events like the overthrow of Saddam Hussein and the overthrow of Moammar Gadhafi, and they feel that they need a nuclear weapon to protect themselves. In the Kim regime, almost all of their legitimacy comes from being seen as tough and standing up to foreign oppressors, and so on. And I think they see it as a very important political symbol domestically.
It’s sort of saying to the people: “Yes, you may not be getting a lot of economic growth, but you are getting protection from foreign invasion and oppression.” The nuclear weapons are a central symbol of technological prowess of the North that the Kim regime has allegedly delivered, a central symbol of standing up to the West, a central symbol of power that the Kim regime thinks of as important for its survival, in addition to it just being important strategically in terms of convincing the United States not to invade and overthrow them. They have now written that they are a nuclear weapons state into their constitution, believe it or not.
They agreed in 2005 that they would abandon all their nuclear programs. The notion that they’re ever going to fulfill that commitment under the current regime seems extraordinarily unlikely. The reality is successive U.S. presidents have said that a nuclear-armed North Korea is unacceptable and intolerable. And for years we’ve been in the business of accepting it and tolerating it.
GAZETTE: Is there a red line that, if crossed, would prompt immediate and dramatic action by the U.S. and allies?
SAMORE: There might be, but it certainly isn’t this. There had already been three nuclear tests, and so I would expect the response to be pretty similar, which is basically diplomatic condemnation and a new U.N. Security Council resolution that would impose new sanctions against North Korea. The big question is whether China will agree to economic sanctions that go beyond targeted sanctions against North Korea’s nuclear and missile program — in other words, sanctions that would affect the economy overall. Up to now, China has not been willing to take that kind of step, mainly for fear of provoking North Korea or causing instability on the Korean Peninsula. My guess is that Beijing is unlikely to accept those kinds of broad economic sanctions even though they’re very frustrated and angry with North Korea. I think the Chinese leadership is not willing to run the risk of creating instability or even creating a conflict on the Korean peninsula.
The North Korean economy is heavily dependent on China for survival. Most of North Korea’s exports of raw materials, especially coal and other commodities, go to China. And without Chinese exports of oil and financial services, the North Korean economy would probably collapse. But China is afraid to use that economic leverage because they’re nervous about provoking the North into doing something rash that might cause a conflict or create instability. The Chinese are afraid that the Korean peninsula could be unified under a government friendly to the United States.
GAZETTE: Given that global condemnation after the 2013 test appear to have had little effect, what viable options are left to contain or halt North Korea’s program? Clearly, diplomacy and sanctions haven’t been successful.
SAMORE: Well, that’s been the problem from the beginning. We don’t have any options to end this program or roll it back. We can’t use diplomacy and sanctions. We can’t use military force, for obvious reasons. And so basically, the only option we have is the hope that eventually the North Korean regime will collapse and that will stop the program. But as long as the current government survives, I think they will continue to pursue their nuclear and missile program, and the best we can do is slow it down. There’s pretty good evidence that in the past we’ve been able to delay decisions to conduct nuclear and missiles tests through behind-the-scenes diplomatic pressure, but it’s only a delay. It doesn’t end it; it just buys you more time.
Every time there’s been a test, we’ve proposed a new sanctions resolution in the U.N., and the Chinese proceed to water it down. So my guess is that we will pull out of the drawer a lot of the previous sanctions proposals that the Chinese objected to in the hopes that this time the Chinese will recognize that they have to go a step further in terms of punishing North Korea.
GAZETTE: So how then does this affect relations with South Korea, China, Russia, and Japan? All have expressed outrage. But moving forward, what are they likely to do, and what role will the U.S. play?
SAMORE: It will lead to a temporary suspension in improvement in relations, especially with South Korea. In the last six months, there have been some indications that the North was looking for improved relations with South Korea, all of which has an economic payoff for them in terms of tourism and other forms of economic assistance — things like resumption of South Korean tourism in the North. Some South Korean companies have been using cheap labor in the North for some industrial activities. All of that went down the drain during the previous South Korean president’s administration.
There’s been some evidence that the North was looking to restore that, and I think all that gets put on hold now, which really, in my mind, raises questions about Kim Jong-un’s judgment. To me, this seems like a particularly stupid thing to do because there’s going to be an economic penalty for it. There may be some domestic political motivation … so I don’t quite know the rationale for conducting the test at this time. It doesn’t seem to be very strong, and it makes me wonder whether this might be another example of poor judgment on his part.
GAZETTE: What about Russia and Japan?
SAMORE: They don’t have much economic leverage.
GAZETTE: So what does the U.S. do?
SAMORE: This is a very well-established diplomatic playbook. We draft a sanctions resolution, which is usually pretty heavy. And then we take it to China, and over a period of weeks we work out a deal with China, and then we take it to the rest of the U.N. Security Council, and they approve it. So this is basically a bilateral diplomatic negotiation between Washington and Beijing, which is then endorsed by the Security Council.
We’ve got lots of language on additional sanctions that have been cut out of previous Security Council resolutions, so we’ll just go back to the same old language and see whether China will be willing to tolerate it. I hope they will, but I think it will be pretty limited because China’s really in a dilemma. They don’t like these nuclear tests, and they would like to constrain and eliminate North Korea’s nuclear program. But they’ve got bigger problems on the peninsula, and, of course, U.S.-China relations are not so great right now.
These interviews have been lightly edited for length and clarity.