What were the new challenges that the ending of the Cold War brought to the United States at the end of the 20th century?

The biggest challenge that the end of the Cold War brought to the United States was in the realm of foreign policy. Basically, the question was: What should the role of the United States be in the post-Cold War world? Then-president George H.W. Bush referred to a "new world order," and intellectual Francis Fukuyama proclaimed the collapse of communism in the Soviet Union and the communist bloc as the "end of history." But the reality was that nobody knew what to expect from the post-Cold War world. The Cold War had offered a sort of stability that vanished with its end. One immediate challenge emerged in the Balkans, where the collapse of communism unleashed long-simmering ethnic tensions that degenerated into a brutal civil war. Eventually, under President Bill Clinton, the United States and NATO launched airstrikes to stop the potential genocide that accompanied this development. During the Bush administration, in 1990, Saddam Hussein's Iraq invaded neighboring Kuwait. The United States and a broad coalition of nations, including Arab leaders, launched "Operation Desert Storm," which successfully drove Iraq from Kuwait. But the Bush and Clinton administrations struggled to find a response to flashpoints in the African nations of Somalia and Rwanda, the latter of which resulted in the genocide of hundreds of thousands of people in that country. So the end of the Cold War created questions of how and to what extent the United States should play a role in shaping the new world order.