The U.S. is no longer an un-rivalled empire dominating the world system. It has suffered a relative decline as a result of its disastrous invasions of Iraq and Afghanistan. That setback was compounded by the global slump, which has weakened America’s hegemony over the world economy. Now the U.S. now faces new international and regional rivals. China is becoming more assertive in Asia and throughout the world. Russia and many other lesser powers are pressing their interests against the U.S. in their own regions. We are witnessing the start of new inter-imperial rivalries that will intensify in the 21st century.