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Hecker Q&A on estimates of North Korea’s nuclear arsenal


On April 22, 2015, the Wall Street Journal published the article “China Warns North Korean Threat is Rising,” reporting on estimates from Chinese and American nuclear experts of the DPRK nuclear arsenal. The article quotes CISAC’s Siegfried Hecker, director of the Nuclear Risk Reduction Project, on his assessment of the North Korean nuclear crisis and presents the estimates of Dr. Hecker’s Chinese counterparts. In the following Q&A, Hecker, who has been an authority in the United States on technical assessments of the progress of the North Korean nuclear program — having visited North Korea seven times since 2004 and having been granted unprecedented access to North Korea’s Yongbyon nuclear facilities — discusses the information presented in the Wall Street Journal article and provides insight both on the nature of technical estimates of the DPRK nuclear arsenal as well as on the critical takeaways from these assessments.

What was the nature of the meeting referenced in the Wall Street Journal article in which China’s estimates were presented?

This meeting was an off-the-record, non-governmental, non-official dialogue on U.S. – China security issues. The discussion on North Korea’s nuclear program was one of many security topics discussed. Both Chinese and American experts made presentations. The headline of the WSJ article is misleading – it is not “China” that made these estimates, but Chinese nuclear experts.

Have you conferred with Chinese nuclear experts about the North Korean nuclear program before the referenced meeting?

As part of my Nuclear Risk Reduction project at Stanford University, I have conferred regularly with nuclear and policy experts in China and Russia, as well as American experts and officials, of course. We have done so since January in 2004, when I first visited the Yongbyon Nuclear Center and returned through Beijing (the normal transit in and out of Pyongyang).

On that trip, North Korean nuclear officials showed me plutonium metal that they had reprocessed from the spent fuel rods that were stored since the beginning of the Agreed Framework in 1994. When the Agreed Framework fell apart in late 2002, Pyongyang expelled the international inspectors and withdrew from the Nonproliferation Treaty.  I believed they showed me their nuclear facilities and the plutonium to try to convince Washington that they had the bomb.

How did these visits inform your assessment of the DPRK nuclear program?

I visited North Korea seven times in total, with four of those visits to the Yongbyon Nuclear Center. After each of these visits, I compared observations and analyses with Chinese nuclear experts. During the first few visits, the Chinese experts and Chinese international relations scholars were quite skeptical of North Korea’s nuclear capabilities. I believe that my observations helped to inform their subsequent analysis since Chinese experts did not have access to Yongbyon at the time.

So what precipitated the change in the perception of your Chinese colleagues of North Korea’s nuclear capabilities?

During the first few years of discussion, my estimates of North Korea’s capabilities exceeded those of Chinese experts.  However, during my most recent visit to Yongbyon in November 2010, North Korean nuclear officials showed me their newly constructed uranium enrichment facility, housing 2,000 modern centrifuges, and the beginning of the construction of an experimental light water reactor. Overhead imagery shows that the exterior of the reactor is essentially complete, that the size of the centrifuge hall has been doubled, and that significant additional construction has occurred in the fuel fabrication complex, where the centrifuge facility is housed.

Pyongyang’s move to augment their limited plutonium production in the 5 MW-electric reactor (at most one bomb’s worth of plutonium per year) with enriched uranium changed the game.

Changed the game, how?

It opened the second path to the bomb and made it difficult to assess North Korea’s nuclear capabilities. Unlike the reactor production of plutonium, centrifuges are easy to hide. So, post-2010 it became more difficult to make accurate estimates, but all of us believed that North Korea enhanced its nuclear capacity significantly.

I published my most recent estimates in an article in the Bulletin of the Atomic Scientists along with a brief history of North Korea’s nuclear build-up. The latest estimates by Chinese nuclear experts now exceed mine. I believe that we base our estimates on the same open-source data.

If you base your estimates on the same information, what accounts for the discrepancies between your assessments and the estimates from your Chinese colleagues?

Developing these estimates is not an exact science. There are huge uncertainties in estimating the enrichment capacity that is likely present at covert sites. One particular problem is the difficulty in assessing how much indigenous capacity North Korea has to make the key materials and components for centrifuges. To demonstrate the great uncertainties, the WSJ article cites a recent report by David Albright of the Institute of Science and International Security that shows the possible range of bomb-fuel capacity in 2020 to vary from 20 to 100 bombs. The Chinese experts’ and my estimates fall within that range.

The Wall Street Journal article reported that American officials recently stated that North Korea possesses an intercontinental ballistic missile with sufficient range to reach the United States. Is the threat of nuclear attack on the United States from North Korea imminent?

I view the threat to the United States posed by an untested missile, the so-called KN-08, with a hypothetical miniaturized nuclear warhead as unrealistic any time in the near future. The KN-08 has not been tested to our knowledge. I believe North Korea would require more long-range missile tests and more nuclear tests to pose a direct threat to the United States.

With the international community’s attention directed toward the U.S.-Iran nuclear deal, what are your thoughts on the analogy made in the article between the Iran Nuclear Deal and the 1994 Agreed Framework with North Korea?

I don’t concur with the analogy of the failings of the Agreed Framework to the potential Iran deal. It is true that North Korea continued to develop uranium enrichment capabilities during the Agreed Framework. However, without the Agreed Framework, North Korea could have produced a nuclear arsenal as large as they have today 10 years earlier. And, by terminating the Agreed Framework, Washington traded the threat of uranium bombs that was at least 10 more years away for plutonium bombs that were built within a year.

Then what is the critical takeaway from your and your Chinese colleagues’ assessments of North Korea’s nuclear capabilities?

The real tragedy, in my opinion, is that whereas in 2003 North Korea likely had no nuclear weapons, it appears to have a rapidly expanding arsenal today. During the past 12 years we have witnessed the North Korean program grow from having the option for a bomb in 2003, to having a handful of bombs five years later, to having an expanding nuclear arsenal now.

Why does an expanding arsenal matter?

I believe it has made Pyongyang increasingly reliant on its nuclear weapons for regime survival and has dimmed the prospect of a denuclearized Korean peninsula. Such an arsenal may instill Pyongyang’s leadership with a false sense of confidence and almost certainly expands what it may think are its tactical and strategic options. The potential for miscalculations and accidents increases, and the consequences will be greater if it has more bombs and more sophisticated bombs with greater reach.