Stanford nuclear experts said they were skeptical of North Korea’s claim that it had detonated a hydrogen bomb this week.

However, they said the test was an important step forward for North Korea’s nuclear program and would have a destabilizing effect on the entire region.

“I don’t believe it was a real hydrogen bomb, but my greatest concern is not so much whether or not they actually tested a hydrogen bomb, but rather that they tested at all,” said Siegfried Hecker, former director of Los Alamos National Laboratory and senior fellow at Stanford’s Center for International Security and Cooperation.

North Korean dictator Kim Jong-un has “a track record of exaggerated statements, hyperbole and outright lies,” according to Scott Sagan, Caroline S.G. Munro professor of Political Science.

“The propaganda machine in North Korea has made all sorts of claims about Kim Jong-un’s personal prowess and his history, and it is totally unsurprising that he might make exaggerated claims about North Korea’s military prowess,” Sagan said.

Former U.S. Secretary of Defense William J. Perry said he also doubted that North Korea had detonated a two-stage hydrogen bomb.

“Whether it’s a hydrogen bomb or not, it’s very dangerous, destabilizing development,” said Perry.

“It’s obvious they’re working to increase the capability and size of their nuclear arsenal and that represents a huge danger to the region and creates major instability and major concerns on the part of South Korea and Japan.”

Many North Korea watchers had been anticipating another nuclear test.

“We’ve thought that the North Koreans could test at any time – that the tunnels were ready, that they could do this at any time – so it would be a political decision, not a technical decision,” said Thomas Fingar, senior fellow at the Freeman Spogli Institute for International Studies.

Hecker said North Korea’s latest nuclear test would move the country closer to being able to miniaturize a nuclear warhead and mount it on a missile, extending the reach of their nuclear weapons.

“They will have achieved greater sophistication in their bomb design – that is the most worrisome aspect,” Hecker said.

“At this point, what makes their nuclear arsenal more dangerous is not so much explosive power of the bomb, but its size, weight and the ability to deliver it with missiles.”

On the diplomatic agenda, the U.S. and its allies will likely push for stronger sanctions in the wake of the tests, according to Kathleen Stephens, a former U.S. Ambassador to the Republic of Korea and William J. Perry fellow at Walter H. Shorenstein Asia-Pacific Research Center (APARC).

“In the UN the U.S., Japan and South Korea will likely look for another, and stronger, UN Security Council resolution, presumably with some efforts to attach to it some teeth and strengthen sanctions,” Stephens said.

The U.S. Congress is currently considering financial sanctions that would cut of all access to U.S. banks for any banks dealing with the North Koreans.

But financial sanctions would likely be less effective in dealing with North Korea than they had been with Iran, according to Fingar.

“It’s like hitting a masochist,” said Fingar.

“North Korea is relatively insulated from the external economy, where Iran wasn’t. Iran had a middle class, you could make sanctions hurt, they could have a real effect. You could make it hard for the North Koreans to buy luxury goods, but at the end of the day, is that going to bring down the regime?”

Financial sanctions against North Korea could have the unintended consequence of also hurting China, said David Straub, associate director of the Korea program at APARC.

“This could be problematic for China because many of the transactions that North Korea conducts would be going thorough Chinese banks, and the Chinese, understandably might not be happy about the US financial sanctions on them, in effect,” Straub said.

Perry recommended that the U.S. reinvigorate diplomatic talks with North Korea in collaboration with China, South Korea, Japan and Russia.

“I would not give up on negotiations with North Korea yet,” Perry said.

“What could have been done many years ago was following through on negotiations with North Korea at the turn of the Century, which were proceeding robustly in the last years of Clinton’s second term, but were abandoned by the Bush Administration...That was a geo-strategic error.”

But Hecker said those negotiations would be harder now.

“I have previously argued that we should focus on three “No’s” for three “Yes’s” – that is no more bombs, no better bombs (meaning no testing) and no export – in return for addressing the North’s security concerns, its energy shortage and its economic woes,” said Hecker.

“This could have worked when I first proposed it 2008 after one of my seven visits to North Korea. It will be more difficult now."

Former Los Alamos National Laboratory director Siegfried Hecker assesses North Korea’s claim to have detonated a hydrogen bomb in an underground nuclear test this week. Hecker is one of the world’s top experts on the North Korean nuclear program. He has visited North Korea seven times since 2004, and is the only Western scientist known to have ever been inside a North Korean uranium enrichment facility. He is currently a senior fellow at Stanford’s Center for International Security and Cooperation, and a research professor of Management Science and Engineering.

Do you believe that North Korea actually detonated a hydrogen bomb in its latest nuclear test?

I don’t believe it was a real hydrogen bomb, but my greatest concern is not so much whether or not they actually tested a hydrogen bomb, but rather that they tested at all. Since this test worked, they will have achieved greater sophistication in their bomb design – that is the most worrisome aspect. This is their fourth test – with each test they can learn a lot.

What makes a hydrogen bomb a more threatening weapon than a conventional atomic bomb?

A hydrogen bomb can be a hundred or a thousand-fold more powerful than a fission bomb. Certainly a blast of a megaton will be much more destructive than the Hiroshima bomb, but the more important part is the ability to deliver at long range and to do it accurately. That is what would threaten the United States and its allies most; even with the size of nuclear blasts they have already demonstrated.

White House officials say that initial data from nearby monitoring stations are not consistent with a hydrogen bomb test. How will we know for sure whether it was a hydrogen bomb or not?

The short answer is that we may never know. The telltale signs of a hydrogen bomb are very difficult to pick up in a deeply buried test. Typically hydrogen bombs have greater explosive power or yield. This test is currently believed to have resulted in a seismic tremor of 5.1 on the Richter earthquake scale. That would make it roughly equivalent to the third nuclear test in February 2013. At that time, North Korea claimed it tested a miniaturized atomic bomb – there was no mention of a hydrogen bomb. My estimate of the yield for the 2013 test is roughly 7 to 16 kilotons – which is in the range of the 13-kiloton Hiroshima blast. As far as destructiveness, a Hiroshima-scale explosion is bad enough. Detonated in Manhattan, it may kill as many as a quarter million people. The power of the 2013 and the current explosion is more consistent with fission bombs than hydrogen bombs.

Can you rule out the possibility that it was a hydrogen bomb?

I find it highly unlikely that the North tested a real hydrogen fusion bomb, but we know so little about North Korea’s nuclear weapons design and test results that we cannot completely rule it out. A modern hydrogen bomb is a two-stage device that uses a fission bomb to drive the second stage fusion device. A two-stage device is very difficult to design and construct, and is likely still beyond the reach of North Korea today. However, by comparison, China’s early nuclear weapon program progressed rapidly. It tested its first fission bomb in 1964 and less than three years later demonstrated a hydrogen bomb – and that was 50 years ago. North Korea has now been in the nuclear testing business for almost 10 years, so we can’t rule anything out for certain.

If it wasn’t a hydrogen bomb, what kind of bomb might it have been?

What may be more likely than a two-stage hydrogen bomb is that they took an intermediate step that utilizes hydrogen (actually hydrogen isotopes) fuel to boost the explosive yield of the fission bomb, a sort of turbocharging. Such a device has a fusion or “hydrogen” component, but is not a real hydrogen bomb. It allows miniaturization – that is making the bomb smaller and lighter. Moreover, it would be the first step toward eventually mastering a two-stage hydrogen bomb.

The most important aspect then is to miniaturize, whether it is a fission bomb, a boosted fission bomb, or a hydrogen bomb. The Nagasaki bomb weighed 5,000 kilograms. It was delivered in a specially equipped B-29 bomber. North Korea wants to demonstrate it has a deterrent. To do so, it needs to be able to credibly threaten the U.S. mainland or our overseas assets. For that, you have to make the bomb (more correctly, the warhead) small enough to mount on a missile. The smaller and lighter, the greater the reach. At this point, what makes their nuclear arsenal more dangerous is not so much explosive power of the bomb, but its size, weight and the ability to deliver it with missiles.

How close is North Korea to being able to credibly threaten a nuclear strike against the mainland United States?

North Korea is still a long way off from being able to strike the US mainland. It has only had one successful space launch. It needs a lot more, but it has a large effort in that direction.

Do you think North Korea conducted this test for political or technical reasons?

North Korea had very strong technical and military drivers for this test, as well as follow-on tests. The political environment is mostly what has constrained it from testing earlier and more often. However, this test demonstrates that Pyongyang is willing to weather the political storm this test will bring. It has done so for all previous tests.

What are your current estimates on the size of North Korea's stockpile of nuclear weapons and materials?

Much like in the area of sophistication of the bomb, we have little information of what North Korea actually possesses. The best we can do is to estimate how much bomb fuel, plutonium and highly enriched uranium, they may have produced and estimate how many bombs they can produce from that stockpile. My best estimate at this time is that they may have enough bomb fuel for 18 bombs with a capacity to make 6 to 7 more annually. That, combined with the increased sophistication they surely achieved with this test, paints a troublesome picture.

How should the U.S. respond?

I am concerned about we haven’t done to date. Washington has lost many opportunities we have had since North Korea began its nuclear weapon production in earnest in 2003. One thing that’s clear is that doing what we and the rest of the world have done so far – half-hearted diplomacy, ultimatums, and sanctions – have failed, so these are not the answer. I have previously argued that we should focus on three “No’s” for three “Yes’s” – that is no more bombs, no better bombs (meaning no testing) and no export – in return for addressing the North’s security concerns, its energy shortage and its economic woes. This could have worked when I first proposed it 2008 after one of my seven visits to North Korea. It will be more difficult now.

A conference that honored the life and scholarly contributions of Stanford economist Masahiko Aoki was held at Stanford. Dozens of friends, family and community members paid tribute to Aoki, the Henri and Tomoye Takahashi Professor of Japanese Studies and Professor of Economics, emeritus, who died in July at the age of 77.

Eleven renowned economists and social scientists gave talks on Aoki’s extensive fields of research in economic theory, institutional analysis, corporate governance, and the Japanese and Chinese economies at the Dec. 4 conference, which was followed by a memorial ceremony the next day.

“When we contacted people to speak at this conference, few people turned us down,” said Stanford professor Takeo Hoshi. “The reason for this is Masa. It shows how much Masa was respected and how much his work is valued.”

The events were hosted by the Japan Program at the Walter H. Shorenstein Asia-Pacific Research Center, the Freeman Spogli Institute for International Studies (FSI), Graduate School of Business, Department of Economics and the Stanford Institute for Economic Policy Research (SIEPR).

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Aoki came to Stanford in 1967 as an assistant professor, held faculty appointments at Kyoto University and Harvard, and returned to Stanford in 1984. He retired to emeritus status at Stanford in 2005.

Throughout the conference, Aoki was described as an astute professor and colleague, valuable mentor and loyal friend by the many speakers and participants who shared works, stories and multimedia featuring their interactions with Aoki.

Aoki pioneered the field of comparative institutional analysis (CIA) with a team of scholars at Stanford: Avner Greif, John Litwack, Paul Milgrom and Yingyi Qian, among others. CIA analyzes and compares different institutions that evolve to regulate different societies.

“Masa had a good background in looking at the economy as a whole, financial institutions as a whole – not just how numbers or actors economically interact – but also the people who interact within a given institutional framework,” said Koichi Hamada, a professor emeritus at Yale University. 

Aoki applied a systematic lens to everything he studied, a “take society as a total entity” approach, Hamada said.

Aoki grew up in Japan, and developed a deep interest in Japanese politics at an early age. He was actively involved in student movements in the early 1960s, at the heart of which was a campaign against a controversial U.S.-Japan security treaty. China became another great interest of his as the country began to undergo economic transformation and modernization.

Throughout his career, Aoki traveled to Japan and China often, and sought to better inform policy debates by engaging scholars, government leaders and journalists there.

He believed in sharing lessons learned from his own scholarly analyses on what constitute institutions, particularly the “people” aspects – the employees, their cognitive abilities and levels of participation.

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Top left to right: Yingyi Qian of Tsinghau University talks with Avner Greif of Stanford University and Hugh Patrick of Columbia University. / Koichi Hamada of Yale University delivers his remarks titled "Masahiko Aoki: A Social Scientist." Bottom: Reiko Aoki, the wife of Masahiko Aoki, listens in to Kenneth Arrow, a professor emeritus at Stanford University. Credit: Rod Searcey

Aoki was not only a scholar of institutions but also a builder of them.

In 2005, Aoki helped oversee the development of the Center for Industrial Development and Environmental Governance at Tsinghua University in Beijing, which held numerous roundtables in its first decade of existence, and continues to this day.

“Amid a time of diplomatic tensions between China and Japan…Masa was able to bring Japanese, Chinese and American economists together to study and do research,” said Yingyi Qian, dean and professor at the school of economics and management at Tsinghua.

At Stanford, Aoki played a leading role in the creation of the Stanford Japan Center and a multi-day conference that convened annually in Kyoto on issues of mutual concern between Asia-Pacific countries and the United States.

Earlier this year, Aoki was hospitalized for lung disease. Even at that stage, he worked tirelessly to revise a paper that examines the institutional development of China and Japan in the late 19^th to early 20^th centuries.

That paper titled, “Three-person game of institutional resilience versus transition: A model and China-Japan comparative history,” was presented at the conference by Jiahua Che, one of two scholars that Aoki asked to finish and publish the work.

Aoki was also fondly remembered for his mentorship of students at Stanford and other universities he taught at.

“He was an original and unique professor – quite different from others that I’ve met in many respects. He was generous with his time, not hierarchical,” said Miguel Angel Garcia Cestona, who studied for a doctorate at Stanford and now teaches at the Universitat Autonoma de Barcelona.

Garcia Cestona, among other former students, spoke of Aoki as a friend and shared memories of their former professor hosting them at his home.

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Masahiko Aoki in Northern California, 2014.

Related Links:

Conference agenda

Stanford obituary

by Kendra Davidson

In 1922, Xiao Youmei, a Chinese scholar and composer, created the original Chinese symphony orchestra to bring the sound of Beethoven to his people for the first time.

On November 12, 2015, Jingdong Cai, associate professor of performance in the Center for East Asian Studies, recreated this historical experience with 15 musicians from the Peking University Orchestra at the Stanford Center in Beijing. “It was something like time travel,” he recalled.  

Read more.