After December 26, 1991, with the fall of the Soviet Union, the bipolarity of the international system was eliminated. In the post-Cold War period, the United States faced the problem, without a defined enemy, of adopting a new foreign policy. To begin analyzing U.S. foreign policy, one must first understand the international system. According to Political Realism, a theory of international thought, the state is the key unit within the acts within the system. These states act according to their key norms, permitted by the system. However, these states are also influenced by internal and external factors that control the way they act. Internal factors include political culture, economic system, leadership within the country, and population. Despite these major factors, the key external factor determining the state's actions and foreign policy is anarchy. Anarchy is the lack of a central government capable of enforcing rules within the international community. This principle implies that the international community is dangerous and could lead to ruin and disparity for any state without rules to govern and mandates that constrain unruly states, creating a system of self-help. To survive within this system a state must generate power or the ability to make others do what they otherwise would not do. Within this power a state could easily fall into the hands of other powers. To gain power, states create alliances or increase their political advantages. The main components of power are soft power and material power. Soft power includes the ability to “make other states want what you want” (Nye). Material power includes wealth to issue rewards and punishments and a large army to instill fear in others… middle of the paper… in any case we will no longer have such sovereignty. However, we should simply resign from our duties, but continue to lead and defend our ideals by taking on a lesser role. As demonstrated by the adoption of some policies of national interest and the adoption of a multilateral vision, which will put a strain on the US economy while allowing it to take an active leading role and at the same time influence other nations with its apparent soft power. " Personal interview. January-February 2011. Yes, Joseph. "The new Rome meets the new barbarians." The Economist [New York] March 2002, article 1 par.: 2-4. Print.Stiles, Kendall W. Case Histories in International Politics. 5th ed. Georgetown: Pearson Education, 2008. Print.Wallerstein, “The Eagle Has Landed.” Foreign Policy [Minneapolis] July-August 2002, Annual Edition -9. Print.