During the seven decades from the nation's entry into World War II in 1941 to the present, economic constraints rarely limited what the United States did in the world. Now that will change. The country's soaring deficits, fueled by the huge costs of the financial crash and of its entitlement programs--Social Security and Medicare--is bringing the era of expansive American foreign policy to an end. In The Frugal Superpower, Michael Mandelbaum, named one of the top 100 global thinkers by Foreign Policy, describes the policies the United States will have to discontinue; assesses the potential threats from China, Russia and Iran; and recommends a more modest American international agenda that can survive today's economic climate.