Since oil began fueling the global economy, governments have employed policies of “energy mercantilism” to secure access to this key input. Critics of these policies claim they are unnecessary because oil can be acquired on global markets. Countries such as China that engage in energy mercantilism are thus neither enhancing their energy security nor threatening others' access to oil. These critics, however, misunderstand the logic of energy mercantilism, which is rooted in the economics and business literatures on supply chain management. Firms and states are correct to worry about access to critical supplies under four conditions: imperfect contracting, supplier collusion, geographic concentration, and high risk of conflict. All of these conditions plague the oil industry. Likewise, the energy mercantilist policies that critics deride are analogous to the strategies that firms adopt to protect their supply chains. China's steps to ensure access to oil have enhanced its energy security and reduced U.S. coercive options toward Beijing. More broadly, the unfolding competition over energy access highlights the lingering power of mercantilism, even in this age of economic globalization and the apparent triumph of market liberalism.

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.

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.

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.