Do Presidents Really Steer Foreign Policy?

The 21st century began with an extraordinary imbalance in world power. The United States was the only country able to project military force globally; it represented more than a quarter of the world economy, and had the world’s leading soft-power resources in its universities and entertainment industry. America’s primacy appeared well established. Americans seemed to like this situation. In the 2012 presidential campaign, both major-party candidates insisted that American power was not in decline, and vowed that they would maintain American primacy. But how much are such promises within the ability of presidents to keep? Was presidential leadership ever essential to the establishment of American primacy, or was that primacy an accident of history that would have occurred regardless of who occupied the Oval Office?