Atlantic Charter to define goals for the post-war world. In December 1941, Japan attacked American and British territories with near-simultaneous offensives against Southeast Asia and the Central Pacific including an attack on the US fleet at Pearl Harbor. These attacks led the United States and United Kingdom to declare war on Japan. Three days later, Germany and Italy declared war on the United States, which the United States reciprocated. During the War, the Big Four powers (the United States, United Kingdom, the Soviet Union, and China) met to plan the post-war world. In an effort to maintain peace, the Allies formed the United Nations, which came into existence on October 24, 1945, and adopted the Universal Declaration of Human Rights in 1948, as a common standard for all member states. The United States worked closely with the United Kingdom to establish the IMF, World Bank and NATO. Pax Americana Pax Americana represents the relative peace in the Western world, resulting in part from the preponderance of power enjoyed by the United States of America starting around the middle of the 20th century. Although the term finds its primary utility in the late 20th century, it has been used in other times in the 20th century. Its modern connotations concern the peace established after the end of World War II in 1945. Post-1945 characteristics The American Century existed through the Cold War and demonstrated the status of the United States as the foremost of the world's two superpowers. After the Cold War, the most common belief held that only the United States fulfilled the criteria to be considered a superpower. Its geographic area composed the fourth-largest state in the world, with an area of approximately 9.37 million km2. The population of the US was 248.7 million in 1990, at that time the fourth-largest nation. In the mid-to-late 20th century, the political status of the US was defined as a strongly capitalist federation and constitutional republic. It had a permanent seat on the United Nations Security Council plus two allies with permanent seats, the United Kingdom and France. The US had strong ties with capitalist Western Europe, Latin America, British Commonwealth, and several East Asian countries (Korea, Taiwan, Japan). It allied itself with both right-wing dictatorships and capitalist democracies. The American Century includes the political influence of the United States but also its economic influence. Many states around the world would, over