In Conversation

The paradoxes of nuclear politics with political scientist Alexandre Debs

The co-author of a new book about the strategic causes of proliferation discusses why some nations choose to acquire nuclear weapons, while others do not.
Image of man walking a tightrope balancing a nuclear bomb.

(Illustration by Michael S. Helfenbein)

President Trump provided a stark reminder of the stakes of nuclear politics when he warned nuclear-armed North Korea to stop making threats or “be met with fire and fury like the world has never seen.”

North Korea’s acquisition of a nuclear bomb marks a key failure in the United States’ 72-year effort to prevent the spread of nuclear weapons. U.S. nonproliferation policy has had success: Only nine nations other than the U.S. have developed nuclear weapons; only eight of those currently possess them: Russia, China, the United Kingdom, France, Israel, India, Pakistan, and North Korea. (South Africa dismantled its nuclear arsenal in the early 1990s.)  Only three — Russia, China, and North Korea — are considered U.S. adversaries.

Portrait of Alexandre Debs
Alexandre Debs

In a new book, “Nuclear Politics: The Strategic Causes of Proliferation,” Yale University political scientists Alexandre Debs and Nuno P. Monteiro explore why certain states have acquired nuclear weapons while others, which seemingly would benefit from possessing them, have not.  Combining game theory and a detailed historical analysis, they define the strategic circumstances under which a state is most likely to seek and acquire the bomb.  

Debs, an associate professor of political science, spoke with YaleNews about their book. An edit transcript of the conversation follows:

What motivated your research?

Nuclear politics is full of paradoxes, making it an intriguing subject. On the one hand, nuclear weapons are the world’s most destructive weapons. They are the ultimate weapon and the great equalizer — even if a state loses a conventional war, if it is nuclear armed, then it can protect its core interests and safeguard its regime. They have been said to revolutionize international relations. Yet on the other hand, they have not been used in battle for 72 years. Also, we have worried a lot about proliferation, but very few states have acquired nuclear weapons.

People naturally worry when they read about nuclear proliferation in the news, but there has been little proliferation since 1945 — nine countries currently possess nuclear weapons — and the rate of proliferation has slowed since the Cold War ended. One of our motivations was whether we should be worrying about proliferation at all. Why is it such a concern when the pace of proliferation has been so slow?

We focus on the security dimension of nuclear weapons. A lot of recent scholarship has focused on other dimensions, like the psychology of leaders or preferences of ruling coalitions. We treat nuclear weapons as weapons and consider not only the benefits that accrue to states that acquire them, but also how the pursuit of nuclear weapons affects relations with other states and how those other states can affect whether a state is successful in acquiring the bomb.

What is your argument?

In short, the argument is that nuclear weapons are the weapons of the weak, but the weak are unlikely to obtain them because other states will intervene. If those other states are enemies, they will either issue threats or launch preventive military strikes. If they are allies, they will offer assurances or threaten abandonment. Acquiring a nuclear weapon requires both the willingness and the opportunity to do so. States become willing when they face a severe threat while lacking the protection of a powerful ally. States have the opportunity when their conventional forces or alliances are sufficient to deter preventive attacks. Few states ever find themselves in this position.    

We study nuclear politics as a strategic relationship between a potential proliferator and its enemies and allies. If a state really wants nuclear weapons, other states may really want to prevent it from acquiring them. We used strategic tools like game theory to analyze those strategic interactions. We covered a lot of history — the book contains 16 case studies, which provides readers a substantial chunk of information on international relations since 1945. We show that the United States has been fairly successful in preventing the spread of nuclear weapons.

When do states seek nuclear weapons?

A state needs to perceive a dire security threat while believing it cannot count on an ally for protection. North Korea is a good example. The armistice signed in 1953 was not followed by a peace treaty, and North Korea views the presence of American troops in South Korea as a severe threat. It did not view the Soviet Union and China as reliable allies. It considered its regime under threat and believed nuclear weapons could provide them a trump card.

In the case of Israel, it had assurances of protection from the United States, but the U.S. did not want to make those assurances public. The Israelis, who had survived the Holocaust, were surrounded by enemy states, and were not confident in America's commitment to protect them, decided to acquire nuclear weapons.

Pakistan sees India as an enemy and has only received limited support from the United States. The Pakistanis did not trust the Americans to protect them. After the Soviets invaded Afghanistan, the U.S. focused on other security goals and turned a blind eye to Pakistan’s nuclear program, which enabled the Pakistanis to develop the bomb.

Why did North Korea succeed in acquiring the bomb?

I think North Korea is unique in the sense that, even though it would not win a military conflict with the United States and South Korea, the nature of geography on the Korean peninsula — Seoul being just 35 miles from the border — enables North Korea to inflict severe damage on South Korea with conventional weapons.

In 1994, the United States considered launching a preventive strike but former President Carter brokered a deal at the last minute. For various reasons having to do with American domestic politics and distrust of the North Korean regime, the framework was abandoned. The Bush administration took a harder line on North Korea than had the Clinton administration, but the military options just aren’t there. Any military intervention would result in an extremely high death toll, which limited the U.S.’s ability to coerce North Korea into abandoning its nuclear weapons program.

Why didn’t South Korea develop a nuclear weapon?

We worry a lot about proliferation, but there are a lot of success stories. South Korea is an example. 

A new book by Yale political scientists Alexandre Debs and Nuno P. Monteiro combines game theory and historical analysis to determine which nations are most likely to seek nuclear weapons.

South Korea is relatively strong compared to North Korea. If nuclear weapons are the weapons of the weak, then the stronger a nation is, the less likely it is to seek to acquire nuclear weapons. Conventional weapons or alliances satisfy its security needs. South Korea’s alliance with the United States is critically important. It started a nuclear program during the Nixon administration, which had urged East Asian allies to invest more heavily in their own defense. The United States soon realized that it preferred to control nuclear proliferation. Does the U.S. really want to be in a situation in which the South Koreans decide whether the conflict escalates into nuclear confrontation?

So far, the U.S. has successfully prevented South Korea and Japan from acquiring nuclear weapons by assuring them that it will provide for their security.

Why has Iran been unable to acquire a nuclear weapon?

Iran is a fascinating case study.  Not many people realize how much the United States was involved in supporting Iran’s nuclear industry before the Islamic revolution. When the Islamic Republic came to power, it considered the nuclear program a white elephant — excessive resources had been devoted to it. They didn’t pursue a nuclear weapon right away.

After the U.S. invaded Iraq in 2003, the Iranian regime became concerned that Tehran would be next. There is some evidence that the Iranians reached out to the Americans to a make a deal to freeze their nuclear program. It was a unique opportunity, but there was pressure within the Bush administration to oppose a deal. “We don’t speak with evil,” was how some put it.

You could see a need from the Iranian perspective to acquire nuclear weapons, but they had little opportunity to do so. Iran would not prevail in a conventional military conflict with the Unites States and Israel, and the international community, led by the U.S., imposed tough sanctions against the regime.

So here is a state that wants nuclear weapons but is unlikely to get them. By imposing stiff sanctions and keeping the military option on the table, the U.S. and the international community was able to strike a deal that has limited Iran’s nuclear program.

What do you hope policymakers take away from your book?

On the whole, U.S. administrations have thought of non-proliferation as a security benefit  — it is a good thing to prevent states from obtaining nuclear weapons. Administrations have varied on their willingness to press that goal given that the United States has many foreign policy goals that sometimes conflict. You can understand why Nixon wanted to turn the page on Vietnam and encourage East Asian allies to take more responsibility for their security, but that policy had consequences regarding proliferation. Future administrations changed course. 

The Trump administration has created a lot of uncertainty. The president’s foreign policy preferences seem to be moving away from the consensus that alliances and security commitments have created peace and stability. As president elect, Trump spoke of Japan and South Korea needing to shoulder more of the burden for their own defense, but since he’s been in office, it seems he has reaffirmed America’s security commitments to those allies. There’s just a lot of uncertainty.

We show that alliances have been vital to the U.S.’s nonproliferation efforts. Previous administration’s non-proliferation policies — assuring allies or using coercive measures when necessary — have largely succeeded. I hope our work will help policymakers to reflect on that successful history and inform their approach to non-proliferation.

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