Ryan Snyder and Benoît Pelopidas respond to Keir A. Lieber and Daryl G. Press's spring 2017 article, “The New Era of Counterforce: Technological Change and the Future of Nuclear Deterrence.”

The nuclear weapons taboo is considered one of the strongest norms in international politics. A prohibition against using nuclear weapons has seemingly shaped state behavior for nearly seven decades and, according to some observers, made nuclear use ‘unthinkable’ today or in the future. Although scholars have shown that nuclear aversion has affected decision-making behavior, important questions about the nuclear taboo remain unanswered. This article seeks to answer a basic question: How durable is the taboo? We develop different predictions about norm durability depending on whether the taboo is based primarily on moral logic or strategic logic. We use the comparable case of the norm against strategic bombing in the 20th century to evaluate these hypotheses. The logic and evidence presented in this paper suggest that the norm of nuclear non-use is much more fragile than most analysts understand.

A sampling of articles in the Spring 2016 issue of the Belfer Center's journal International Security.

International Security is America’s leading journal of security affairs. 
IS was ranked first in impact factor for 2014 among 85 journals of international relations in the annual “Journal Citation Reports”® released by Thomson Reuters. International Security’s 2014 Impact Factor is the highest of any international relations journals.

This policy brief is based on “The New Era of Counterforce: Technological Change and the Future of Nuclear Deterrence,” which appears in the spring 2017 issue of International Security.

For decades, nuclear deterrence has depended on the impossibility of a first strike destroying a country’s nuclear arsenal. Technological advances, however, are undermining states’ abilities to hide and protect their nuclear arsenals. These developments help explain why nuclear-armed states have continued to engage in security competition: nuclear deterrence is neither automatic nor permanent. Thus, the United States should enhance its counterforce capabilities and avoid reducing its nuclear arsenal.

Assessing the risk of nuclear attack-by-proxy turns on the question of whether a state could sponsor nuclear terrorism and remain anonymous. A leader could rationalize such an attack—and entrust terrorists with a vitally important mission—only if doing so allowed the sponsor to avoid retaliation. After all, if a leader did not care about retaliation, he or she would likely conduct a nuclear strike directly. Giving nuclear weapons to terrorists makes sense only if there is a high likelihood of remaining anonymous after the attack.

Many experts consider nuclear terrorism the single greatest threat to U.S. security. The fear that a state might transfer nuclear materials to terrorists was a core justification for the invasion of Iraq in 2003 and, more recently, for a strike against Iran’s nuclear program. The logical basis for this concern is sound: if a state could orchestrate an anonymous nuclear terror attack, it could destroy an enemy yet avoid retaliation. But how likely is it that the perpetrators of nuclear terrorism could remain anonymous? Data culled from a decade of terrorist incidents reveal that attribution is very likely after high-casualty terror attacks. Attribution rates are even higher for attacks on the U.S. homeland or the territory of a major U.S. ally—97 percent for incidents in which ten or more people were killed. Moreover, tracing a terrorist group that used a nuclear weapon to its state sponsor would not be difficult, because few countries sponsor terror; few terror groups have multiple sponsors; and only one country that sponsors terrorism, Pakistan, has nuclear weapons or enough material to manufacture them. If leaders understand these facts, they will be as reluctant to give weapons to terrorists as they are to use them directly; both actions would invite devastating retaliation.

Jack Snyder replies to Keir Lieber's Fall 2007 International Security article, "The New History of World War I and What It Means for International Relations Theory."

New historical evidence reveals that World War I, far from being accidental, was provoked by German leaders who hoped to dominate the European continent, fully aware that the conflict would be long and bloody. They did not have a blueprint for quick victory embodied in the Schlieffen Plan; they did not misjudge the nature of modern war; and they did not lose control of events and attack out of fear of their enemies moving first. This new historiography challenges the core concepts of defensive realism and calls for a reinterpretation of the war as it relates to causes of conflict.

Can the United States destroy the long-range nuclear arsenals of China and Russia ? Keir Lieber and Daryl Press argue that not only does the United States have a potent first-strike capability, but that the nuclear balance will continue to shift in its favor, creating significant implications for international relations and U.S. foreign policy.