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Counting nuclear warheads in the public interest

Longtime Nuclear Notebook readers know that we typically take an in-depth look at arsenals around the world to reveal, as much as possible, what kind of nuclear weapons are deployed, where they are, and in what numbers. In this issue of the Bulletin of the Atomic Scientists, we are going to do something different and take stock of what we've been able to accomplish in more than 180 columns over the past 28 years, and the role the Notebook has come to play in public debate.

The Notebook originated with researchers at the Natural Resources Defense Council (NRDC), who in the early 1980s saw a need for a publicly available resource that provided the basic facts about US nuclear weapons: how many there were, what they looked like, where they were deployed, and how and where they were made. This led to the Nuclear Weapons Databook series, |1| a set of standard reference works still in use. After three volumes devoted to the United States, the NRDC produced a fourth volume about Soviet weapons in 1988 and a fifth volume about the British, French, and Chinese nuclear arsenals in 1994.

The Notebook began as a way to update information in the Databook series, and has been published in every issue of the Bulletin since May 1987 (archived Bulletin issues from 1987 to 1998 are available at: Issues from 1999 to 2015 are available at: Over the years, we have watched it become one of the most respected and widely used open sources for trustworthy information about the status and history of nuclear forces worldwide. Now the Notebook is used every day by journalists, scholars, and activists to describe, analyze, and campaign on nuclear weapons issues. Even government officials use it to discuss issues that would otherwise have to rely on classified information. Because factual and reliable information is so important to the public debate, the Notebook is not hidden behind a password or paywall, but freely available to all. Whereas nuclear weapons were once spoken of in hushed voices with layers of classification, the Databook series and the Notebook have undermined this situation, allowing anyone to participate in the discussion.

The NRDC's nuclear team developed the methodology for researching and analyzing nuclear forces that we still use as our benchmark for providing accurate estimates on the various arsenals. Vigorous use of the US Freedom of Information Act (FOIA) has been key to all of the volumes; together we and the NRDC team have made thousands of requests over the years.

Beyond counting nuclear warheads, our column has also been an important source of information on the weapon systems that deliver them--including missiles, submarines, and aircraft--as well as on yields, tests, locations, and budgets. Much of this information, too, comes from keeping close watch on newly declassified documents from the US government, many obtained via FOIA requests. We also garner information from congressional hearings, specialty magazines, and confidential sources.

Creating estimates for other nuclear-armed states can be more challenging because not all provide as much information as the United States. Britain and France have published some information about their arsenals, but much is still unavailable. Russia does not currently release substantial information, but past arms control agreements have yielded some data that is still useful for understanding its current posture. For Russia and the remaining nuclear-armed states (China, Pakistan, India, North Korea, and Israel), estimates rely more on information from Western intelligence organizations, expert studies, news media reports, and commercial satellite imagery.

The Notebook team has been remarkably stable over the years. Robert S. Norris has co-authored it from the beginning, first with William M. Arkin from 1987 until 2002, and since 2001 with Hans M. Kristensen. The Notebook was produced under the auspices of the NRDC until 2010 when the Federation of American Scientists took over the supporting role. Continuity and institutional memory are essential for developing sources, knowing where to look for information, and being able to provide accurate estimates and histories.

Right on target

The first Notebook, in 1987, focused on US activities, documenting the presence of US nuclear weapons in Europe (some of which are still there), development of the Advanced Cruise Missile (which was retired early in 2007), plans to deploy Lance short-range missiles to South Korea (which never happened), development of the Midgetman intercontinental ballistic missile (which was canceled in 1992), deployment of Tomahawk sea-launched cruise missiles (which were scrapped in 2012), production of B-IB bombers (which have since been denuclearized), and the accuracy of the MX ICBM (also known as the Peacekeeper, which was retired in 2005). That first Notebook also provided a seven-year overview of US and Soviet strategic nuclear forces (Norris and Arkin, 1987).

Since then, as nuclear arsenals have changed significantly, the Notebook has enabled the public to trace changes in global stockpiles over time. Thanks to the Notebook, we know how much progress has been made in reducing global nuclear warhead inventories since the Cold War--but also that the pace of reductions has recently slowed (Kristensen and Norris, 2013).

Over the years, we've had opportunities to check our own accuracy, and the results have often been remarkable. In May 2010, for example, when the Obama administration declassified the entire history of the US nuclear weapons stockpile, we had just completed the draft Notebook on US nuclear forces for that year (Norris and Kristensen, 2010). Our stockpile estimate of 5,100 warheads was only 13 warheads off from the official number, 5,113 (Department of Defense, 2010). Considering that the stockpile size was a closely held national secret, we are proud of this achievement, a testament to the quality of the methodology developed by the NRDC's Nuclear Weapons Databook team.

The November 1999 and January 2000 issues of the Bulletin published particularly important historical Notebooks. They provided the first overview of where US nuclear weapons had been deployed during the Cold War, information that was the result of an intense FOIA campaign to obtain a Pentagon report entitled History of the Custody and Deployment of Nuclear Weapons: July 1945 through September 1977. Although some information remained classified and was redacted from the version released, the remaining information enabled us to reconstruct a global table of what types of nuclear weapons were deployed to specific countries during specific time periods (Norris et al., 1999). Sometimes the host countries didn't even know the weapons were there. For instance, Japan--which was the target of two atomic bomb attacks and has a law against nuclear weapons on its territory-- learned from the Notebook that there were US nuclear weapons on Chichi Jima and Iwo Jima, an enormous and varied US nuclear arsenal on Okinawa, US nuclear bombs (without their fissile cores) stored on the mainland at Misawa and Itazuki air bases (and possibly at Atsugi, Iwakuni, Johnson, and Komaki air bases as well), and nuclear-armed US Navy ships stationed in Sasebo and Yokosuka (Norris et al., 2000).

An international perspective

While the United States has increased transparency surrounding its nuclear arsenal over the years, that is not necessarily the case with other nuclear-armed states. Britain (Norris and Kristensen, 2013) and France (Norris and Kristensen, 2008) have provided limited transparency, but it is much more difficult to develop accurate estimates of the arsenals kept by Russia, China, Pakistan, India, Israel, and North Korea. None of these countries provides detailed information, and Western intelligence agencies have decreased what they say in public about them, which makes the role of the Notebook particularly important.

After a window of some transparency during the 1990s following the breakup of the Soviet Union, and information reported under the Strategic Arms Reduction Treaty (START) from 1995 through July 2009, Russia has largely returned to nuclear opacity. With no substantial official information currently being disclosed, the Notebook provides a unique source for understanding the history, status, and trend of Russia's nuclear forces and is widely used by news media and analysts in the country itself. The information it provides is particularly important now because renewed concern in the West about Russian nuclear modernization has prompted some to make exaggerated claims about a nuclear arms buildup. |2| In contrast, the Notebook offers balanced and fact-based information and analysis on the status and trend of Russian nuclear forces.

The Notebook has also provided important information about China (e.g., Kristensen and Norris, 2013), another nuclear-armed country that does not share official information about its arsenal. Creating estimates for Chinese nuclear forces, while challenging, has been important for dispelling incorrect reports. In 2011, news reports about Chinese underground facilities resulted in widely circulated claims that the Chinese stockpile might include as many as 1,800 to 3,000 warheads. |3| In contrast, the Notebook estimates that China has roughly 250 warheads, an assessment that was shared by Gen. Robert Kehler (Ret.), the commander of US Strategic Command, in a 2012 interview with journalists in which he said: "I do not believe that China has hundreds or thousands more nuclear weapons than what the intelligence community has been saying... The Chinese arsenal is in the range of several hundred" nuclear warheads (Kristensen, 2012).

Countries that have joined the nuclear club more recently have arsenals that are smaller but nonetheless important to monitor and understand because of the risks of regional nuclear competition and the possibility that the weapons might be used. The Notebook's analyses of Pakistan's (e.g., Kristensen and Norris, 2011) and India's arsenals are widely used in both countries as the benchmark for what the other side has, and there, too, we've had the opportunity to check our work against other sources. In 2011, The New York Times cited "officials and outsiders familiar with the American assessments" of Pakistan suggesting that the country's arsenal "now ranges from the mid-90s to more than 110" (Sanger and Schmitt, 2011). The assessment largely matched the Notebook estimate.

Most recently, in December 2014, the Notebook did an exhaustive review of Israel's nuclear arsenal and concluded that claims it has 200 to 400 warheads are probably exaggerated and that the country's stockpile is more likely in the range of roughly 80 nuclear warheads (Kristensen and Norris, 2014b). Getting the size and composition right is important because it hints at Israeli intentions, and can therefore have a significant effect on threat perceptions in the Middle East and the potential nuclear aspirations of other countries in the region.

Keeping on

Today, the Notebook is the most popular web feature from the Bulletin's subscription journal, and our research forms the basis of our ability to answer the many calls we get from journalists reporting on the status and trends of nuclear forces. Notebook research is also used as the basis for producing the world nuclear forces overview in the Yearbook of the Stockholm International Peace Research Institute (SIPRI). Hans Kristensen has co-authored the SIPRI Yearbook since 2001, before which Robert S. Norris and the former NRDC Nuclear Weapons Databook team wrote it. The SIPRI Yearbook is translated into Russian, Chinese, and Arabic.

To be sure, efforts to produce each Notebook can be tedious and time-consuming. Monitoring reports about new developments in nine nuclear-armed countries is an enormous undertaking in itself, and only the first step. Information and sources must be checked and double-checked, and the new information must be analyzed to see how it impacts current and earlier estimates. The draft Notebook must be reviewed by other experts, and the crucial editing process with Bulletin staff can go on for several rounds. Release of new official information doesn't always match the Notebook production schedule, so the final edits are sometimes late--very late; we have often missed a deadline but never an issue. All of this work would not have been possible without the generous support of numerous private foundations over the years, including the Carnegie Corporation of New York, the Ford Foundation, the John D. and Catherine T. MacArthur Foundation, the New Land Foundation, the Ploughshares Fund, the W. Alton Jones Foundation, and many more.

As the world changes over the next 28 years and countries' nuclear arsenals grow or shrink, our goal is to keep doing what we've been doing since before the end ofthe Cold War: produce and disseminate the Notebook as a valuable resource for journalists, scholars, analysts, and activists as they debate and discuss the future of nuclear weapons--and by extension the future of humanity.

[Source: By Robert S. Norris and Hans M. Kristensen, Bulletin of the Atomic Scientists 2015, Vol. 71(1) 85-90, Chicago, Jan15]


Author biographies

Robert S. Norris is a senior fellow with the Federation of American Scientists in Washington, DC. A former senior research associate with the Natural Resources Defense Council, his principal areas of expertise include writing and research on all aspects of the nuclear weapons programs of the United States, the Soviet Union and Russia, the United Kingdom, France, and China, as well as India, Pakistan, and Israel. He is the author of Racing for the Bomb: General Leslie R. Groves, the Manhattan Project's Indispensable Man (Steerforth, 2002) and co-author of Making the Russian Bomb: From Stalin to Yeltsin (Westview, 1995). He co-authored or contributed to the chapter on nuclear weapons in the 1985- 2000 editions of the SIPRI Yearbook (Oxford University Press) and has co-authored Nuclear Notebook since 1987.

Hans M. Kristensen is the director of the Nuclear Information Project with the Federation of American Scientists (FAS) in Washington, DC. His work focuses on researching and writing about the status of nuclear weapons and the policies that direct them. Kristensen is a coauthor of the world nuclear forces overview in the SIPRI Yearbook (Oxford University Press) and a frequent adviser to the news media on nuclear weapons policy and operations. He has co-authored Nuclear Notebook since 2001. Inquiries should be directed to FAS, 1725 DeSales St. NW, Sixth Floor, Washington, DC 20036; (202) 546-3300.


1. See Natural Resources Defense Council (undated). [Back]

2. See, for example, Inhofe (2014). [Back]

3. For high estimates of China's nuclear arsenal, see Esin (2012); Karber (2011: Slide 331); Stephens (2011). [Back]

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