H ow strong are normative prohibitions on state behavior? We examine this question by analyzing anti-nuclear norms, sometimes called the "nuclear taboo," using an original survey experiment to evaluate American attitudes regarding nuclear use. We find that the public has only a weak aversion to using nuclear weapons and that this aversion has few characteristics of an "unthinkable" behavior or taboo. Instead, public attitudes about whether to use nuclear weapons are driven largely by consequentialist considerations of military utility. Americans' willingness to use nuclear weapons increases dramatically when nuclear weapons provide advantages over conventional weapons in destroying critical targets. Americans who oppose the use of nuclear weapons seem to do so primarily for fear of setting a negative precedent that could lead to the use of nuclear weapons by other states against the United States or its allies in the future.

Nuclear deterrence rests on the survivability of nuclear arsenals. For much of the nuclear age, “counterforce” disarming attacks—those aimed at eliminating an opponent's nuclear forces—were nearly impossible because of the ability of potential victims to hide and protect their weapons. Technological developments, however, are eroding this foundation of nuclear deterrence. Advances rooted in the computer revolution have made nuclear forces around the world considerably more vulnerable. Specifically, two key approaches that countries have relied on to ensure arsenal survivability since the dawn of the nuclear age—hardening and concealment—have been undercut by leaps in weapons accuracy and a revolution in remote sensing. Various methods, evidence, and models demonstrate the emergence of new possibilities for counterforce disarming strikes. In short, the task of securing nuclear arsenals against attack is far more difficult than it was in the past. The new era of counterforce challenges the basis for confidence in contemporary deterrence stability, raises critical issues for national and international security policy, and sheds light on one of the enduring theoretical puzzles of the nuclear era: why international security competition has endured in the shadow of the nuclear revolution.

For nearly half a century, the world's most powerful nuclear-armed states have been locked in a condition of mutual assured destruction. Since the end of the Cold War, however, the nuclear balance has shifted dramatically. The U.S. nuclear arsenal has steadily improved; the Russian force has sharply eroded; and Chinese nuclear modernization has progressed at a glacial pace. As a result, the United States now stands on the verge of attaining nuclear primacy, meaning that it could conceivably disarm the long-range nuclear arsenals of Russia and China with a nuclear first strike. A simple nuclear exchange model demonstrates that the United States has a potent first-strike capability. The trajectory of nuclear developments suggests that the nuclear balance will continue to shift in favor of the United States in coming years. The rise of U.S. nuclear primacy has significant implications for relations among the world's great powers, for U.S. foreign policy, and for international relations scholarship.

This chapter describes the unique attributes of nuclear weapons that make them the most effective instruments of deterrence ever created. It discusses the intensely competitive nature of international politics that has endured despite the nuclear stalemate. Stalemate exists when neither adversary in a war can escape destruction and emerge victorious in any practical sense of the term. The chapter talks about the Clausewitzian definition of war as an extension of politics, by which other means becomes an absurdity since no rational goal of statecraft can entail suicidal destruction. It emphasizes why strategic stalemate should not only deter war but also allow countries to abandon a wide range of costly and risky policies designed to increase their security.