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Iran: The Nuclear Challenge

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Nonproliferation, Arms Control, and Disarmament

As the P5+1 nations (United States, France, Britain, Russia, China, and Germany) and the world continue to grapple with Iran's nuclear program, seven CFR scholars map the objectives, tools, and strategies for dealing with one of the most vexing foreign policy problems, in a new CFR ebook.

Edited by former deputy national security adviser Robert D. Blackwill, the book serves to provide clarity on policy choices. "Authors have made no effort to persuade readers on behalf of any particular American action," he explains.

"The aim of this volume is not to tell the reader what to think but rather how to think about Iran's nuclear activities and the options for addressing them," writes CFR President Richard N. Haass in the foreword.

Professors: To request an exam copy, contact Please include your university and course name.

Bookstores: To order bulk copies, please contact Ingram. Visit, call 800.234.6737, or email ISBN: 978-0-87609-535-5

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Reviews and Endorsements

Iran: The Nuclear Challenge is perhaps the most comprehensive and nuanced analysis of how we should think about Iran's nuclear program. Assembling a cast of distinguished scholars and seasoned policy practitioners, this CFR volume examines the political, economic, and military strategies associated with the Iranian nuclear problem. Each author carefully fleshes out the contours and consequences of available U.S. policy choices, providing the reader a deep understanding of the Iranian nuclear dilemma. Iran: the Nuclear Challenge will undoubtedly enhance our debate on the most challenging security issue confronting the United States today.

Stephen J. Hadley, former national security adviser

Iran: The Nuclear Challenge unravels and isolates the choices available to the United States as it faces the possibility of Iranian nuclear weapons capabilities—an illuminating work even for those already well versed in the issues. The authors, all senior fellows at CFR, provide insightful personal analysis as well as the tools necessary to form one's own judgments, affording a meaningful exercise in foreign policy decision-making. With the mission of informing readers not what to think, but how to think about Iran's nuclear activities and U.S. options, Iran: The Nuclear Challenge will remain of significant value to practitioners and students alike.

Samuel R. Berger, chair of Albright Stonebridge Group and former national security adviser

Excerpt Up

Introduction: What Do We Know?

Ray Takeyh

At present, Iran can best be described as a country determined to preserve for itself the option of acquiring nuclear weapons capability at some future date: to shorten, to the greatest extent possible, the time it will take to build these weapons (and to warn the world) once the decision is made to do so, by developing dispersed, hardened dual-use nuclear fuel cycle capabilities; and to seek shelter from international nonproliferation pressure in the Nuclear Nonproliferation Treaty's (NPT) promise of access to nuclear technology for peaceful purposes.

In chronological form, the basic contours of the Iranian nuclear program are as follows:

  • In the mid-1980s, the Khomeini regime secretly decided to restart a nuclear program, including preparatory work for the acquisition of a nuclear weapon, that had begun under the shah. This decision is believed to have been influenced by the devastation inflicted on Iran by Iraq's use of chemical weapons during the Iran-Iraq War.
  • From about 1990 on, Iran worked to develop its own nuclear fuel cycle infrastructure—uranium mining, conversion, and enrichment—and heavy-water production for a heavy-water reactor for the production of plutonium. In the mid-1990s, Iran began to secretly purchase and take delivery of uranium enrichment centrifuges from the A. Q. Khan network.[1] Iran began to test these centrifuges in 2000.
    • In 2001, Iran began to construct its main enrichment facility in Natanz, approximately two hundred miles south of Tehran. The plant is constructed to eventually accommodate fifty thousand centrifuges, giving Iran the ability to produce massive quantities of enriched uranium.
    • In 2002, secret Iranian fuel cycle activities were publicly revealed, fundamentally changing the diplomatic landscape. From this point on, Britain, France, and Germany (the EU3) and the International Atomic Energy Agency (IAEA) began to play much more significant roles in the diplomatic effort to address the problem. The IAEA conducted limited inspections of Iran's previously clandestine facilities and discovered additional evidence of Iran's concealment of undeclared fuel cycle activities.[2]
    • In late 2003, the EU3 persuaded the government of President Mohammad Khatami to suspend its enrichment program and accept the NPT Additional Protocol.[3] Furthermore, the U.S. intelligence community assessed that, in the fall of 2003, the Iranian government halted its clandestine research and development program for nuclear weapons—but not the nuclear fuel cycle systems, such as centrifuges, needed to produce the fissile material for a possible weapon. (British intelligence services surveying the same information concluded that though Iran halted weaponization activities in 2003, it subsequently resumed them.) In sum, the circumstantial evidence strongly suggests that Iran is, at a minimum, aiming to develop a nuclear weapons capability. The U.S. military presence in Afghanistan, on Iran's eastern border, and in Iraq, on Iran's western border, was presumably a factor in Iran's 2003–2004 nuclear decision-making.
    • The EU3's agreement with the Iranian government collapsed after the election of Mahmoud Ahmadinejad in 2005.
    • In 2009, the government of Iran disclosed to the IAEA the existence of a new uranium enrichment facility at Fordow, outside Qom; this facility had already been detected by Western intelligence. The IAEA believes that enrichment operations began there in December 2011, that the facility's purpose is to enrich uranium beyond the 5 percent U-235 concentration achieved at Natanz, and that it is undergoing construction designed to further expand its capacity to eventually accommodate more than three thousand centrifuges. The Fordow facility is better protected than the Natanz facility and thus less susceptible to destruction by air or missile strikes.

Since 2007, U.S. intelligence services have asserted that no evidence suggests that Supreme Leader Ali Khamenei has made the final decision to construct nuclear weapons, but it is clear that he is accumulating the necessary resources and technologies that will provide him with that option. "They are certainly moving on that path, but we don't believe that they have actually made the decision to go ahead with a nuclear weapon," stressed James Clapper, the director of National Intelligence, in his testimony to the Senate Select Committee on Intelligence in February 2012.[4] Although the acquisition of these fuel cycle capabilities could be justified under the same legal theory that Iran is entitled to the benefits of nuclear technology for civil, peaceful purposes, Iran elected to carry out this work secretly and often in violation of its nuclear safeguards commitments to the IAEA.

The Diplomatic Context: The 1990s and Bushehr

The United States has been attempting to stop or at least delay the Iranian nuclear problem since at least the mid-1990s, when Iran contracted with the Russian Ministry for Atomic Energy to complete the construction of the pressurized water reactor nuclear power plant at Bushehr. A German firm began, but did not complete, the construction of the Bushehr complex in 1975, and the reactors had been damaged during the Iran-Iraq War.

The construction of the Bushehr reactor complex was the most visible element of the Iranian nuclear program, and the Clinton administration focused its diplomacy on attempting to dissuade the Russian government from providing nuclear assistance to Iran. The administration was partially successful: it persuaded Russia to not provide the uranium enrichment technology and heavy-water reactor also sought by Iran, and to both supply and retrieve the nuclear fuel that would eventually power the Bushehr reactors.

The Clinton administration's diplomacy toward the Iranian nuclear program had two critical handicaps. The first was that, at the time, Iran was in good standing as a nonnuclear weapons state party to the 1968 Nuclear Nonproliferation Treaty. The central bargain in the NPT is that the nonnuclear weapons states party to the treaty foreswear the acquisition of nuclear weapons; in return, they are guaranteed access to nuclear technology for peaceful purposes. In the mid-1990s, as it does today, Iran argued that it had an international legal right to benefit from civil nuclear power, as many other nations have. In a formal legal sense, the Clinton administration's opposition to the sale of nuclear technology to Iran turned on its assertion that Iran had a covert nuclear weapons program, and therefore was not in good standing with the NPT and not entitled to unbridled access to technology that would accelerate its ability to break out of its NPT commitments. This argument worked reasonably well in Washington and Tel Aviv, but the United States could not prove its case to the rest of the world.

Thus the second handicap had to do with the intelligence on the Iranian nuclear weapons program. In the mid-1990s, the U.S. intelligence community suspected the existence of a covert nuclear weapons program in Iran, but the evidence was almost entirely circumstantial, highly classified, or both. This made it next to impossible to rally broad-based international support around a diplomatic effort to stop Iran's program, or even to talk constructively with the Iranian government about the matter.

Today, unlike the 1990s, there is extensive direct evidence of Iranian efforts to deceive the international community, in violation of its NPT and IAEA safeguards agreements, about its development of dual-use nuclear fuel cycle capabilities. Any concrete information regarding whether Iran has made efforts to construct nuclear weapons ("weaponize") is not publicly available.

The Bushehr reactors began operation under IAEA safeguards in 2010. In part because of the success of U.S. diplomacy toward Iran's chief nuclear supplier (Russia), the direct contribution of Bushehr to the Iranian nuclear weapons program is modest because there is no way that any significant quantity of weapons-usable fissile material can be diverted from Bushehr without several years' notice to the international community.

In addition to Bushehr, Iran has declared fourteen nuclear facilities and nine locations outside those installations where nuclear research is being conducted pursuant to its safeguard obligations to the IAEA. For instance, the latest IAEA report suggests that Natanz contains 54 installed cascades amounting to 9,156 centrifuges. Not all of these cascades are operational; as a result, 8,088 centrifuges were being fed nuclear fuel for enrichment purposes. The same report also states that Iran has 5,451 kilograms of enriched uranium at below 5 percent level in hand. (All the centrifuges at this installation are the more primitive IR-I models, but Iran is known to have experimented with more advanced machines.)

Although it is clear that Iran has focused on uranium enrichment as the mainstay of its fissile material production capability, it has not neglected plutonium—the other fissile material commonly used in nuclear weapons—paths to nuclear empowerment. The heavy-water facilities in Esfahan and the nearly completed plant in Arak point to the fact that Iran's plutonium capabilities are also advancing. Although much of the focus of the international community is on Iran's growing enrichment capabilities, Tehran has attempted to diversify its nuclear portfolio, giving its leaders multiple avenues to achieve a nuclear weapons capability if they elect to do so.

Weaponization Timetable

The question of how long it will take the Islamic Republic to assemble a weapon, if it decides to do so, is at the core of the present international crisis.

The weaponization timetable question is extremely complex and includes extensive technical uncertainties. U.S. intelligence assessments of this question are highly classified, drawing on not just sensitive sources and methods but also the U.S. government's own nuclear weapons expertise.

Before offering an assessment of the Iranian weaponization timetable, two essential framing points should be made.

First, every country has the potential to become a nuclear weapons state. Some countries—Japan, for example—would have a short timetable because of advanced civil nuclear facilities. Other countries such as Saudi Arabia, Egypt, Brazil, Australia, and Nigeria lack the same civil nuclear capacity and so would have a much longer road to travel, but they could certainly get there eventually. Iran lies somewhere in the middle.

The laws of physics, the distribution of natural resources and of basic scientific information, and the efficiency of global commerce rule out the possibility of precluding any determined state's eventual acquisition of nuclear weapons. The appropriate metric for judging nonproliferation and disarmament agreements is thus not whether they eliminate a country's option of acquiring nuclear weapons, which is impossible, but instead the time they reliably extend a country's weaponization timetable.

Second, when countries build nuclear weapons, they have a wide range of design decisions to make, and these decisions will determine not just when they will have a nuclear weapons capability but also what that capability will be. These decisions include, but are by no means limited to

  • whether to optimize centrifuge operations for material conservation (ratio of feed uranium to unit of enrichment), cost efficiency (operating costs of centrifuges), maximizing production of particular quantities for particular enrichment levels, material purity, or any other technical parameter inherent in an enrichment cascade;
  • whether the feedstock fed into an enrichment cascade is natural uranium (0.7 percent U-235) or partially enriched (1 to 20 percent U-235), as partially enriched uranium can be increased to highly enriched uranium (90 percent U-235) more quickly and with less energy and natural uranium;
  • how to optimize weapons design for material efficiency (allowing more weapons for a given quantity of fissile material), reliability (generally allowing fewer but less efficient weapons), safety, weight, yield, and use control;
  • whether to conduct weaponization work in secret or in a manner that provides obvious internationally observable indicators (such as expelling IAEA inspectors and diverting material from safeguarded facilities);
  • whether to rely on designs derived from foreign sources or publicly available data, or to indigenously develop new designs;
  • whether to produce abroad or fabricate internally the nonfissile components of the weapon;
  • whether to develop nuclear weapons delivery systems simultaneously or sequentially with weapons development;
  • whether to design weapons to withstand the physical stresses of ballistic reentry or the lesser ones of air or conventional delivery;
  • how tightly to compartmentalize the weapons development program, and how to recruit, train, and manage the technical personnel needed to work within it;
  • how many weapons to attempt to acquire, and over what time period (that is, whether to acquire a small number as quickly as possible, or build a larger arsenal steadily); and
  • whether and how to test the weapons and weapon delivery systems.

The historical record now offers about two dozen examples of countries that have developed nuclear weapons, have considered doing so, or are doing so currently. Despite the many unknowns and uncertainties, what is quite clear is that no two countries do it precisely the same way. Each makes decisions based on its capabilities, strategic context, internal politics, and learning from others.

Thus, in considering the Iranian weaponization timetable, the important issues are the assumptions about what the Iranian nuclear weapons objectives are and how the Iranian government will go about designing and building its nuclear weapons capability.

If one assumes that Iran aspires to have only a few testable nuclear weapons but to have them as soon as possible, then it is logical to also assume that it will optimize its centrifuge cascade to maximize the production of highly enriched uranium (HEU); opt for a weapons design that is simple and reliable, but not highly efficient from a material conservation or a military deployment perspective; and carry out all these activities simultaneously. Such a weapon would more likely be kept in a laboratory than given to operational units. Nongovernment experts believe that if Iran made the decision to enrich to a higher level today, it could produce enough weapons-grade uranium for one bomb in four months.[5] The same experts estimate that by the end of 2012 the time might be as little as one month.[6] However, this would require Iran to use its safeguarded facilities, a development unlikely to escape detection. Extrapolating from these estimates leads to public estimates that it would take Iran about a year to produce such a nuclear weapon if it decided to do so.[7] After it has this basic weapons capability, Iran would have to continue the long, difficult development process of producing more fissile material, modifying its weapons designs to make them more useful and efficient, and figuring out how to deploy the weapons on delivery systems, making them militarily useful.

But the timetable is entirely different if one assumes that the government of Iran has a longer time frame and more extensive nuclear ambitions. Say, for example, that Iran aspires not to have a few weapons in a laboratory next year but instead one hundred weapons fielded, mated with delivery vehicles, and deployed in the field within a decade. In that case, the timetable would of course be much longer and, most important, the various technical tasks—construction of production and storage facilities, installation and testing of fissile material production systems, procurement of raw materials and technical components, production of fissile material, management of waste products, recruitment and training of technical personnel, design of weapons, construction of weapons, testing of weapons, integration of weapons with delivery systems, and so on—would be carried out more sequentially and deliberately than in the rapid breakout scenario.

Building a nuclear weapon requires a state to perform a wide range of discrete, complex technical tasks, and then to integrate the output of these tasks coherently and logically. The tasks can be done simultaneously—which is generally more difficult and error prone—or sequentially. For this reason, a decision to delay progress in a particular aspect of a nuclear weapons program does not necessarily delay achievement of a state's overall strategic objectives in its desired time frame; in some cases, delay in one area may even help by allowing time, and freeing resources, for the other areas to catch up.

This point is central to the nonproliferation value of a diplomatic outcome that suspends only a particular aspect of Iran's current enrichment operations. Depending on one's assumptions of Iran's strategic objectives, such an outcome may have no impact whatsoever on when Iran achieves the nuclear weapons capability it wants—that is, it will not reliably extend the weaponization timetable and might even help Iran.

The Internal Context: Iran's Politics and Deliberations

At a government level, for the past seven years there is no question that President Ahmadinejad has framed the nuclear issue as a matter of national sovereignty and greatness, and that the resistance of international pressure to curtail the nuclear program has become, if not the raison d'être, then at least a pillar of the struggling Islamic republic. The roots of this Iranian position are complex but clearly relate to Iran's difficult strategic position, surrounded by dangerous neighbors; to Iran's unique identity as the custodian of an ancient, great Persian nation and the center of Shia Islam; and to Iran's fragmented domestic politics.

The trajectory of Iran's nuclear program suggests that it rests on a more formidable scientific infrastructure than often assumed. Iran, in many ways, is an outlier in the history of proliferation: nearly every middle power that has obtained the bomb has had substantial assistance from an external patron. China acquired from the Soviet Union not just technical advice but also the means of building a nuclear reactor, weapon designs, and a supply of ballistic missiles. China in turn provided Pakistan enough enriched uranium for two bombs, helped with the construction of its enrichment facility and plutonium reactors, and furnished bomb designs. Israel received from France a nuclear reactor, underground plutonium reprocessing plant, and weapon designs. India, which has long claimed its nuclear program as an indigenous accomplishment, conveniently leaves out the fact that it received a nuclear reactor from Canada and twenty tons of heavy water from the United States. Isolated and ostracized, South Africa comes closest to Iran's predicament, in that it had to rely on internal resources for constructing the bomb, but it did receive tritium, which is critical for the explosion of thermonuclear weapons, from Israel.

Although Iran received Russian assistance in completing its lightwater reactor, which is difficult to misuse for weapons purposes, and, ominously, rudimentary centrifuges from the A. Q. Khan network, Tehran never enjoyed the type of external patronage that other proliferators garnered. Moreover, no state has confronted such systematic attempts to disrupt its nuclear program through technology denial and computer virus penetration. That Iran has crossed successive technical thresholds, has managed to sustain an elaborate and growing enrichment network, and is working on a new generation of centrifuges are all indications of its scientific acumen.

What made this possible? The 1980s were a calamitous decade for science in Iran, as a revolutionary assault on the universities and the prolonged war with Iraq deprived the educational sector of funds and state support. But this changed in the 1990s, despite sanctions and export controls imposed on Iran after the 1979 revolution, as the political elites sought to revive scientific research. New organizations such as the Zanjan Institute for Advanced Studies in Basic Sciences and the Institute for Theoretical Physics and Mathematics were created; old institutions such as Sharif University of Technology were revived. The Atomic Energy Organization, which was protected by then speaker of the parliament Ayatollah Hashemi Rafsanjani even in the heady days of revolutionary turmoil, enjoyed a new management team and greater state allocations. The results have been impressive: the number of scientific papers produced by Iranian scholars in internationally recognized journals has increased dramatically, and many universities have enough resources and faculty expertise to offer their own doctoral programs.

Iran's scientists have emerged as strong nationalists determined to transcend factional politics and provide their country the full spectrum of technological discovery, including advances in nuclear science. Iran's pariah status has ironically engendered an esprit de corps within its scientific community. Researchers resent being shunned by their international colleagues, and are annoyed at being excluded from collaborative work with Western centers of learning that are crucial to scientific advancement. In today's Iran, rulers and scientists have crafted a national compact whereby the state provides the resources and the scientists furnish their expertise. A dedicated corps of scientific nationalists is committed to providing its country with the capacity to reach the heights of technological achievement.

All this is not to suggest that a change in Iranian government has not had a measurable impact on its strategic calculus. Given its protracted conflict with the United States, many in Iran consider the acquisition of nuclear weapons capability an important objective. The newspaper Kayhan openly called for acquiring "knowledge and ability to make nuclear weapons that are necessary in preparation for the next phase of the battlefield."[8] Ali Larijani, a leading figure in the Islamic Republic, has similarly stipulated that "if Iran becomes atomic Iran, no longer will anyone dare to challenge it because they would have to pay too high of a price."[9] Nuclear weapons may have been sought as tools of deterrence by previous Iranian regimes, but for many today they are a critical means of solidifying Iran's preeminence in the region. As such, a hegemonic Iran is assisted by a robust and extensive nuclear infrastructure.

The primary supporters and drivers of the nuclear program within the Iranian government are elements associated with Supreme Leader Ali Khamenei. Through command of central institutions, such as the Revolutionary Guards and the Guardian Council, they have enormous influence on national security planning. A fundamental tenet of their ideology is that the Islamic Republic is in constant danger from predatory external forces, necessitating military self-reliance. This perception was initially molded by a revolution that sought not just to defy international norms but also to refashion them. The passage of time and the failure of that mission have not necessarily diminished widespread suspicions of the international order and its primary guardian, the United States.

At the core, all disarmament agreements call on a state to forgo a certain degree of sovereignty in exchange for enhanced security. Once it renounces its weapons of mass destruction program, a state can be assured of support from the international community should it be threatened by another state possessing such arms. This implied trade-off has no value for many in Iran. Iran's prolonged war with Iraq has done much to condition the Iranian worldview and behavior. Iraq's use of chemical weapons against Iran—with impunity, if not tacit acceptance of Western powers—has reinforced Iran's suspicions of international order. For many within the Islamic Republic's leadership, the only way to safeguard Iran's interests is to develop an independent nuclear deterrent.

Beyond the legacy of the Iran-Iraq War, the international community's demand that Iran relinquish its fuel cycle capabilities has aroused the leadership's nationalistic impulses. Historically the subject of foreign intervention and the imposition of capitulation treaties, Iran is inordinately sensitive to its national prerogatives and sovereign rights. The rulers of Iran perceive that they are being challenged not because of their provocations and previous treaty violations, but because of superpower bullying. In a peculiar way, the nuclear program and Iran's national identity are fused in the imagination of many Iranians. To stand against the United States on this issue is to validate one's revolutionary ardor and sense of nationalism. Thus, the notion of compromise and acquiescence has limited utility to Iran's aggrieved nationalists.

The one issue that provokes a slight but perceptible disagreement within the governing bloc is the necessity of negotiations. Elements within the Revolutionary Guards dismiss diplomacy and suggest that Washington is not interested in proliferation but instead merely exploiting the nuclear issue to multilateralize its coercive policy. Given the immutable hostility of the United States to Iran, any concessions on the nuclear program would lead only to further impositions. Thus, they dismiss negotiations and call for Iran to press ahead with its activities regardless of international concerns and sensitivities.

The ultimate arbiter of Iranian politics and the person responsible for setting the national course remains Khamenei. Thus far Khamenei has found much to recommend in the Revolutionary Guard perception. He has echoed their claims in stressing that any "setback will encourage the enemy to become more assertive."[10] A supreme leader who has survived a myriad of internal challenges and the external threat of American intervention, he seems at ease with nuclear advocacy. Yet Khamenei cannot always afford bellicosity. He has accepted the importance of diplomatic engagement and has maintained Iran's basic commitment to the NPT. Thus far, the supreme leader has opted for a more judicious and incremental approach to nuclear empowerment. It is a strategy that has served him well as Iran has succeeded in expanding its nuclear infrastructure and has transgressed a series of Western red lines. The price for such advances has been increasing economic penalties and a degree of international isolation. How Khamenei balances the nuclear program with the economic well-being of his country and whether that calculus changes as Iran encounters financial distress will determine the nature of Iran's nuclear path.


  1. ^ "A.Q. Khan and Onward Proliferation from Pakistan," in Nuclear Black Markets: Pakistan, A.Q. Khan, and the Rise of Proliferation Networks, International Institute for Strategic Studies, May 2, 2007, pp. 70–71.
  2. ^ Anthony H. Cordesman and Khalid R. Al-Rodhan, "Iranian Nuclear Weapons? The Uncertain Nature of Iran's Nuclear Programs," Center for Strategic and International Studies, working paper, April 12, 2006, pp. 33–36.
  3. ^ Ibid, pp. 36–40.
  4. ^ James Risen and Mark Mazzetti, "U.S. Agencies See No Move by Iran to Build a Bomb," New York Times, February 24, 2012,
  5. ^ David Albright, Paul Brannan, Andrea Stricker, Christina Walrond, and Houston Wood, "Preventing Iran from Getting Nuclear Weapons: Constraining Its Future Nuclear Options," Institute for Science and International Security, March 5, 2012,
  6. ^ Olli Heinonen, "The 20 Percent Solution," Foreign Policy, January 11, 2012, 20_percent_solution.
  7. ^ Albright et al., "Preventing Iran."
  8. ^ Quoted in Ray Takeyh, Hidden Iran: Paradox and Power in the Islamic Republic (New York: Times Books, 2006), p. 150, from archconservative newspaper Keyhan, February 21, 2006.
  9. ^ Farhang-i Ashti, November 30, 2005 (website in Farsi).
  10. ^ Islamic Republic News Agency, March 3, 2010 (website in Farsi).