The shape, structure and features of the new international system and its structure in the Post-Cold War era have been the subject of intense debates among the scholars and students of international relations discipline. Notwithstanding, questions still beg to be answered on the structure of the new international system and how it impacts the foreign policy behavior of state entities, and in particular, that of a superpower such as the United States. The present article intends to look at the emergence of the new international system and its characteristics through the prism of relevant theories of international politics, with special emphasis on Kenneth Waltz’s neo-liberalism. It will also try to explain the pattern of behavior of major actors and great powers in the new system. Finally, the paper will analyze the role of the U.S. in the new system, and compare its pattern of behavior during and after the Cold War.