The United States remains very powerful — especially when compared with some putative opponents like Iran — but its capacity to lead security and economic orders in every corner of the world has been diminished by failures in Iraq (and eventually, Afghanistan), by the burden of debt accumulated over the past decade, by the economic melt-down in 2007-2008, and by the emergence of somewhat stronger and independent actors in Brazil, Turkey, India, and elsewhere. … If it the United States remains far and away the world's strongest state, its ability to get its way in world affairs is declining.
Drezner fires back:
It Walt overestimates America's influence during the Cold War, he also underestimates American influence now. The funny thing about the "stronger and independent actors in Brazil, Turkey, India, and elsewhere" is that they're siding with the United States on multiple important issues. Coordination between Turkey and the United States on the Arab Spring has increased over time, and their policy positions on Iran are converging more than diverging. Brazil has turned a cold shoulder to Iran and has been warier about China's currency manipulation and rising influence in Latin America. India seems perfectly comfortable to be a partner in America's Pacific Rim pivot, as are Australia, Japan and South Korea.