The United States is uniquely endowed with a position in the Western Hemisphere that spans North America, from the east, the Atlantic Ocean, to the west, the Pacific Ocean. It is one of the world's top three countries with the largest territories, and has extremely rich resources. From 1775 to 1791, the United States launched a revolution from a colony to becoming the largest country in America. The smoothness of its founding and development is unparalleled in the world. By 1890, it had become the world's largest economy and had defeated Spain, a maritime power. Since the United States advocated the Monroe Doctrine in 1823, its influence in South America had steadily increased. To this day, South America has always been regarded as the backyard of the United States, and its influence on the politics, economy and culture of South American countries has grown quite far-reaching
Although the United States has become the largest economic power, it had maintained a low profile early on. When the First World War broke out (7-28-1914 to 11-11-1918), the United States had been avoiding participation and remained neutral from 1914 to 1917 until Germany and Mexico negotiated an attack on the United States (A telegram was revealed by Britain). The U.S. joined the war as an ally in April 1917, but the actual increase in sending troops was nearly the spring of 1918. Therefore, although all major European countries suffered heavy losses in World War I, the United States became a victor without suffering much damage but gaining benefits. After the war, the Paris Peace Conference proposed the establishment of the League of Nations. Although U.S. President Woodrow Wilson agreed to participate in it, the idea was rejected by the U.S. Senate. This showed that Americans (public opinion) were not actively interested in participating in international affairs.
Japan provoked the Sino-Japanese War on July 7, 1937, and Germany attacked Poland on September 1, 1939, which opened the beginning of the premeditated Second World War in Asia and Europe respectively. Japan had a sinister plan to invade and conquer the whole of China and Asia, while Germany had the ambition to seize Europe. The United States once again stayed out of the way initially, boosting its international trade and earning a lot of war money. It was not until December 7, 1941, that Japan decided to attack Pearl Harbor to destroy the U.S. Navy, fearing that it would not be able to rely on the U.S. to supply strategic materials, such as coal, iron, and oil, then the U.S. declared war on Japan. Four days later, Germany declared war on the United States. Once again, the United States won World War II as a victor with the advantage of its late entry into the war and its strong national support and military manufacturing capabilities. The U.S. had become the leader and beneficiary of the Allied Powers towards the tail end of the war. The surrender of Germany and Japan ended World War II in 1945. The United States defeated Germany and helped Europe to recover, and bombed Japan with atomic bombs and occupied Japan. The U.S. thus became the world's most powerful superpower after WW II.
Post-World War II, the League of Nations disintegrated and the United Nations was formed. The United Nations is a democratic structure established under the leadership of the world’s major powers. Each member state In the UN General Assembly has an equal vote, but there is a Security Council above it. Resolutions of the General Assembly must be approved by the Security Council to be effective. In the Security Council, there are five permanent members, namely the United States, Russia, France, Britain, and China, and ten members who are elected for a period of two years and cannot be re-elected for consecutive terms. This structure can operate reasonably smoothly under strong leadership if behaved fair and just. The U.S. economy has grown to 40% of the world economy. Hence, even with Russia leading the Soviet Union in confronting the West, the United States could still lead the United Nations and its Security Council with its super-power status of the world's largest economy..
When the U.S. economy accounts for 40% of the global economy, the U.S. is indeed the number one nation in the world. Not only all its Western allies were following the lead of the U.S., but nearly the entire world had to accept the influence of the U.S. Therefore, post-World War II, the second half of the 20th century (especially with the collapse of the Soviet Union in 1991) is the century of the United States. This has made Americans feel proud and exceptional and believe in American exceptionalism. This feeling does not mean that the Americans have the ambition of territorial hegemony. This is reflected in the fact that the United States has not invaded the territories of its neighboring countries, like Canada and Mexico. But the United States has the mentality of maintaining its economic status. Being a capitalist country, the U.S. has been using its resources and capital to maintain its economic power, an economic hegemony.
The U.S. has gotten used to being the number one economic power, but she has been mindful of others threatening her economic status. When Japan’s economy was rising to be the world’s second largest economy in the 1980’s, the U.S. felt threatened and crashed Japan’s growth by forcing her to accept the Plaza Accord. With the economy of the communist bloc being weak, the U.S. was essentially behaving as the leader of a unipolar world. However, entering the 21st century, the rapidly rising China surpassed Japan as the world’s second largest economy in 2010. To the U.S. China’s rise is far more threatening than Japan or Germany. China not like Japan is not only not controllable militarily (Japan is bound by the U.S.-Japan mutual defense treaty and U.S. military bases in Japan), but also not limited in economic growth (China has 1.4 billion people with a GDP growth rate three times or more of that of the U.S.). This explains the panicky behavior of the U.S. in recent years towards China in the trade war, economic and technology sanctions and diplomacy and military confrontation.