Iran's President Hassan Rouhani waits to address the 68th United Nations General Assembly at UN headquarters in New York, September 24, 2013
Iran's President Hassan Rouhani waits to address the 68th United Nations General Assembly at UN headquarters in New York, September 24, 2013   
Ray Stubblebine / Reuters


Colin H. Kahl


Kenneth Waltz is probably right that a nuclear-armed Iran could be deterred from deliberately using nuclear weapons or transferring a nuclear device to terrorists ("Why Iran Should Get the Bomb," July/August 2012). But he is dead wrong that the Islamic Republic would likely become a more responsible international actor if it crossed the nuclear threshold. In making that argument, Waltz mischaracterizes Iranian motivations and badly misreads history. And despite the fact that Waltz is one of the world's most respected international relations theorists, he ignores important political science research into the effects of nuclear weapons, including recent findings that suggest that new nuclear states are often more reckless and aggressive at lower levels of conflict.


Waltz correctly notes that Iran's leaders, despite their fanatical rhetoric, are fundamentally rational. Because Iran's leadership is not suicidal, it is highly unlikely that a nuclear-armed Iran would deliberately use a nuclear device or transfer one to terrorists. Yet even though the Islamic Republic is rational, it is still dangerous, and it is likely to become even more so if it develops nuclear weapons.

Iran's government currently sponsors terrorist groups and supports militants throughout the Middle East, in part to demonstrate a capability to retaliate against the United States, Israel, and other states should they attack Iran or undermine its interests. If the Iranian leadership's sole concern was its own survival and it believed that a nuclear deterrent alone could give it enough protection, then as a nuclear state, it might curtail its support for proxies in order to avoid needless disputes with other nuclear powers.

But Iran is not a status quo state, and its support for terrorists and militants is intended to be for more than just defense and retaliation. Such support is an offensive tool, designed to pressure and intimidate other states, indirectly expand Iran's influence, and advance its revisionist agenda, which seeks to make Iran the preeminent power in the Middle East, champion resistance to Israel and "arrogant powers" in the West, promote its brand of revolutionary Islamist ideology, and assert its leadership in the wider Islamic world.

Tehran currently calibrates its support for militants and sponsorship of terrorism to minimize the risks of a direct confrontation with more powerful states. But if Iranian leaders perceived that a nuclear arsenal provided a substantially more robust deterrent against retaliation, they would likely pursue their regional goals more aggressively.

Specifically, a nuclear-armed Tehran would likely provide Hezbollah and Palestinian militants with more sophisticated, longer-range, and more accurate conventional weaponry for use against Israel. In an effort to bolster the deterrent capabilities of such allies, Iran might consider giving them "dual-capable" weapons, leaving Israel to guess whether these systems were conventional or armed with chemical, biological, or nuclear material. A nuclear-armed Iran might also give its proxies permission to use advanced weapons systems instead of keeping them in reserve, as Tehran reportedly instructed Hezbollah to do during the militant group's 2006 war with Israel.

A nuclear-armed Iran, believing that it possessed a powerful deterrent and could thus commit violence abroad with near impunity, might also increase the frequency and scale of the terrorist attacks against U.S. and Israeli targets carried out by Hezbollah and the Quds Force, the covert operations wing of Iran's elite Islamic Revolutionary Guard Corps. And a bolder Iran might increase the number of Revolutionary Guard forces it deployed to Lebanon, allow its navy to engage in more frequent shows of force in the Mediterranean, and assert itself more aggressively in the Persian Gulf and the Strait of Hormuz.

To further enhance its image in the eyes of domestic and regional audiences as the leader of an anti-Western resistance bloc, a nuclear-armed Iran might respond to regional crises by threatening to use all the means at its disposal to ensure the survival of the Assad regime in Syria, Hezbollah, or Palestinian groups. And Iran might be emboldened to play the spoiler in the Israeli-Palestinian peace process by encouraging large-scale militant attacks and might try to destabilize its neighbors through more coercive diplomacy and subversion in Iraq and the Gulf states.

The growing influence of "principlist" hard-liners in Tehran makes those possibilities even more likely. The principlists' view of the world is shaped by their ideological belief in the inevitability of U.S. decline, Israeli defeat, and Iranian ascendance. They see the competition with the United States and Israel as a zero-sum game. If Iran obtains a nuclear weapon, the principlists will see it as a confirmation of their convictions and push the Iranian government further in the direction of risk and provocation.

To be sure, a nonnuclear Iran already engages in many destabilizing activities. But equipped with nuclear weapons, Tehran would likely dial up its trouble-making and capitalize on its deterrent to limit the response options available to threatened states.


"History shows that when countries acquire the bomb, they feel increasingly vulnerable and become acutely aware that their nuclear weapons make them a potential target in the eyes of major powers," Waltz argues. "This awareness discourages nuclear states from bold and aggressive action."

In writing this, Waltz ignores a long history of emerging nuclear powers behaving provocatively. In 1950, for example, Soviet leader Joseph Stalin gave North Korea the green light to invade South Korea, thus beginning the Korean War. Stalin apparently assumed (incorrectly) that the United States was unlikely to respond because the Soviets had by then developed their own nuclear weapons. Waltz also claims that China became less aggressive after going nuclear in 1964. But in 1969, Mao Zedong authorized Chinese troops to attack Soviet forces on the Chinese-Soviet border. The attack was meant to warn Moscow against border provocations and to mobilize domestic Chinese support for Mao's revolution. Like Stalin before him, Mao was probably confident that China's recently acquired nuclear capabilities would limit the resulting conflict. (In the end, the border clashes produced a larger crisis than Mao had expected, raising the possibility of a Soviet nuclear strike, and China backed down.)

Waltz also asserts that "India and Pakistan have both become more cautious since going nuclear." But Pakistan's development of nuclear weapons has in fact facilitated its strategy of engaging in low-intensity conflict against India, making the subcontinent more crisis-prone. As the political scientist S. Paul Kapur has shown, as Islamabad's nuclear capabilities have increased, so has the volatility of the Indian-Pakistani rivalry. Since 1998, when both India and Pakistan openly tested nuclear devices, Islamabad has appeared more willing to back militant groups fighting in disputed Kashmir and to support groups that have conducted terrorist attacks elsewhere in India. Furthermore, in 1999, Pakistan sent conventional forces disguised as insurgents across the Line of Control in the Kargil district of Kashmir, triggering a limited war with India. This move was encouraged by the Pakistanis' belief that their nuclear deterrent placed clear limits on India's ability to retaliate with conventional weapons. Additionally, over the past decade, Pakistani-backed militants have engaged in high-profile terrorist attacks inside India itself, including the 2001 attack on the New Delhi parliament complex and the 2008 Mumbai attacks.

Waltz writes that "policymakers and citizens in the Arab world, Europe, Israel, and the United States should take comfort from the fact that history has shown that where nuclear capabilities emerge, so, too, does stability." In fact, the historical record suggests that competition between a nuclear-armed Iran and its principal adversaries would likely follow the pattern known as "the stability-instability paradox," in which the supposed stability created by mutually assured destruction generates greater instability by making provocations, disputes, and conflict below the nuclear threshold seem safe.

During the Cold War, for example, nuclear deterrence prevented large-scale conventional or nuclear war between the United States and the Soviet Union. At the same time, however, the superpowers experienced several direct crises and faced off in a series of bloody proxy wars in Korea, Vietnam, Afghanistan, Angola, Nicaragua, El Salvador, and elsewhere. A recent statistical analysis by the political scientist Michael Horowitz demonstrated that inexperienced nuclear powers tend to be more crisis-prone than other types of states, and research by another political scientist, Robert Rauchhaus, has found that nuclear states are more likely to engage in low-level militarized disputes with one another, even if they are less likely to engage in full-scale war.

If deterrence operates the way Waltz expects it to, a nuclear-armed Iran might reduce the risk of a major conventional war among Middle Eastern states. But history suggests that Tehran's development of nuclear weapons would encourage Iranian adventurism, leading to more frequent and intense crises in the Middle East. Such crises would entail some inherent risk of a nuclear exchange resulting from a miscalculation, an accident, or an unauthorized use -- a risk that currently does not exist at all.

The threat would be particularly high in the initial period after Iran joined the nuclear club. Once the superpowers reached rough nuclear parity during the Cold War, for example, the number of direct crises decreased, and the associated risks of nuclear escalation abated. But during the early years of the Cold War, the superpowers were involved in several crises, and on at least one occasion -- the 1962 Cuban missile crisis -- they came perilously close to nuclear war. Similarly, a stable deterrent relationship between Iran, on the one hand, and the United States and Israel, on the other, would likely emerge over time, but the initial crisis-prone years would be hair-raising. Although all sides would have a profound interest in not allowing events to spiral out of control, the residual risk of inadvertent escalation stemming from decades of distrust and hostility, the absence of direct lines of communication, and organizational mistakes would be nontrivial -- and the consequences of even a low-probability outcome could be devastating.


Because Waltz is sanguine about the effects of Iranian nuclearization, he concludes that "the United States and its allies need not take such pains to prevent the Iranians from developing a nuclear weapon." Waltz believes that the only utility of continued diplomacy is to maintain "open lines of communication," which "will make the Western countries feel better able to live with a nuclear Iran," and he argues that "the current sanctions on Iran can be dropped."

Waltz is wrong. The threat from a nuclear-armed Iran might not be as grave as some suggest, but it would make an already volatile Middle East even more conflict-prone. Preventing Iran from crossing the nuclear threshold should therefore remain a top U.S. priority. Because a preventive military attack on Iran's nuclear infrastructure could itself set off a series of unpredictable and destabilizing consequences, the best and most sustainable solution to Iran's nuclear challenge is to seek a negotiated solution through a combination of economic pressure and diplomacy. It is possible to oppose a rush to war with Iran without arguing, as Waltz does, that a nuclear-armed Iran would make the world a better place.

COLIN H. KAHL is an Associate Professor at Georgetown University's Edmund A. Walsh School of Foreign Service and former Deputy Assistant Secretary of Defense for the Middle East. He is also a Senior Fellow at the Center for a New American Security and a co-author of its report Risk and Rivalry: Iran, Israel, and the Bomb, from which this response is adapted.


In arguing that a nuclear-armed Iran would represent an unacceptable threat to the United States and its allies, Colin Kahl rejects my contention that states tend to become more cautious once they obtain nuclear weapons and claims that I minimize the potential threat of an emboldened Islamic Republic. He accuses me of misreading history and suggests that I overestimate the stability produced by nuclear deterrence. In fact, it is Kahl who misunderstands the historical record and who fails to grasp the ramifications of nuclear deterrence.

In Kahl's view, new nuclear states do not necessarily behave as status quo powers and can instead be highly revisionist. Seeking a precedent, he highlights the fact that the Soviet Union encouraged North Korea to launch a potentially risky invasion of South Korea in 1950, shortly after the Soviets had tested their first nuclear bomb. But Kahl neglects to explain the context of that decision. Some time before, U.S. Secretary of State Dean Acheson had publicly identified the United States' security commitments in Asia; defending South Korea was not among them. The United States had also signaled its lack of interest in protecting the South Koreans by declining to arm them with enough weapons to repel a Soviet-backed invasion by the North. The Soviet Union therefore had good reason to assume that the United States would not respond if the North Koreans attacked. In light of these facts, it is difficult to see Stalin's encouragement of the invasion as an example of bold, revisionist behavior. Contrary to Kahl's claims, the beginning of the Korean War hardly supplies evidence of Soviet nuclear adventurism, and therefore it should not be understood as a cautionary tale when considering the potential impact that possessing a nuclear arsenal would have on Iranian behavior.

Kahl seems to accept that nuclear weapons create stability -- or a form of stability, at least. But he notes -- as do most scholars of nuclear matters, myself included -- that nuclear stability permits lower-level violence. Taking advantage of the protection that their atomic arsenals provide, nuclear-armed states can feel freer to make minor incursions, deploy terrorism, and engage in generally annoying behavior. But the question is how significant these disruptive behaviors are compared with the peace and stability that nuclear weapons produce.

Kahl points to the example of Pakistan, whose nuclear weapons have probably increased its willingness to wage a low-intensity fight against India, which makes the subcontinent more prone to crises. As Kahl correctly argues, Pakistan's increased appetite for risk probably played a role in precipitating the so-called Kargil War between India and Pakistan in 1999. But the Kargil War was the fourth war fought by the two countries, and it paled in comparison to the three wars they fought before they both developed nuclear weapons. In fact, the Kargil conflict was a war only according to social scientists, who oddly define "war" as any conflict that results in 1,000 or more battlefield deaths. By historical standards, that casualty rate constitutes little more than a skirmish. Far from proving that new nuclear states are not swayed by the logic of deterrence, the Kargil War supports the proposition that nuclear weapons prevent minor conflicts from becoming major wars. Indeed, nuclear weapons are the only peace-promoting weapons that the world has ever known, and there is no reason to believe that things would be different if Iran acquired such arms.

Kahl also frets that a nuclear-armed Iran would step up its support for terrorist groups. Terrorism is tragic for those whose lives it destroys and unnerving for countries that suffer from it. But the number of annual fatalities from international terrorism is vanishingly small compared with the casualties wrought by major wars. Of course, like Kahl, I would not welcome increased Iranian support for Hezbollah or an increased supply of more potent Iranian arms to Palestinian militants. And I, too, hope for a peaceful resolution of the Israeli-Palestinian conflict and the disputes between Israel and its neighbors. But the last several decades have not offered much reason to believe those goals can be easily attained, and I would rather see the possibility of major war reduced through nuclear stability, even if the price is an increase in disruptive activities and low-level conflict.

Just a few months ago in these pages, Kahl eloquently expressed his opposition to a proposed preventive strike on suspected Iranian nuclear facilities, warning that it could spark a regional war ("Not Time to Attack Iran," March/April 2012). I agree. But Kahl and I differ on what the United States can achieve in its showdown with the Islamic Republic. Kahl appears to believe that it is possible for the United States to forgo risky military action and still prevent Iran from obtaining nuclear weapons through a combination of sanctions and diplomacy. I strongly doubt that. Short of using military force, it is difficult to imagine how Iran could be prevented from acquiring nuclear weapons if it is determined to do so. That outcome would produce a lamentable possible increase in terrorism and lower-level conflict. But the many benefits of regional stability would far outweigh the costs.

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