This essay appears in Foreign Affairs this month, authored by Keir Leiber and Daryl Press. Read the entire thing.
During the Cold War, many scholars and policy analysts believed that MAD made the world relatively stable and peaceful because it induced great caution in international politics, discouraged the use of nuclear threats to resolve disputes, and generally restrained the superpowers' behavior. (Revealingly, the last intense nuclear standoff, the 1962 Cuban missile crisis, occurred at the dawn of the era of MAD.) Because of the nuclear stalemate, the optimists argued, the era of intentional great-power wars had ended. Critics of MAD, however, argued that it prevented not great-power war but the rolling back of the power and influence of a dangerously expansionist and totalitarian Soviet Union. From that perspective, MAD prolonged the life of an evil empire.
This debate may now seem like ancient history, but it is actually more relevant than ever -- because the age of MAD is nearing an end. Today, for the first time in almost 50 years, the United States stands on the verge of attaining nuclear primacy. It will probably soon be possible for the United States to destroy the long-range nuclear arsenals of Russia or China with a first strike. This dramatic shift in the nuclear balance of power stems from a series of improvements in the United States' nuclear systems, the precipitous decline of Russia's arsenal, and the glacial pace of modernization of China's nuclear forces. Unless Washington's policies change or Moscow and Beijing take steps to increase the size and readiness of their forces, Russia and China -- and the rest of the world -- will live in the shadow of U.S. nuclear primacy for many years to come.