Abstract
The United States which has played a major role in the fate of the bipolar international system during the Cold War, has remained as the main actor in shaping the international system, after the Cold War as well. To accept the US as the only superpower directs the world is one of the most popular issues. Today it is a great debate, whether multipolar or unipolar international system is more convenient to ensure the enduring peace and stability. To end this discussion we have to determine the impacts of the unipolar and the multipolar international systems on the world firstly, and examine the effects of the United States' politics in the structure and mechanism of the present international system secondly.This work investigates the foreign policy applied by the United States to maintain its leadership on one side, and the process of the balance policies towards the other great powers on the other side.