American imperialism is a general notion that in many ways, the United States constitutes an empire. The idea of American imperialism is usually mentioned in tandem with the idea that the country is the global hegemon. While this concept could relate to periods when the United States practiced so-called imperial policies as opposed to when it was isolationist or not expansionist, in modern times, the term tends to encompass American political ideologies, American exceptionalism and numerous powers the United States possesses that are not possessed by other countries.
The term American imperialism could identify the United States as an inherently imperial power that self-justifies its own expansion and either the domination or incorporation of other parties into the American power scheme. Early efforts to settle the Americas by English religious pilgrims and their conception of the region as a land of religious salvation are said to have given rise to the idea that the whole land constituted a divine gift and was given to the religious settlers. This may have fed the idea that the United States would have a special mission and status among other countries -- a view that has survived in the world. Politically, the ideology of Manifest Destiny developed that envisioned the eventual American conquest of the entire region from the East Coast to the then distant Pacific West Coast. John L. O'Sullivan is said to have coined the term Manifest Destiny in an 1845 article promoting the annexation of Texas and an ensuing policy of expansion.
The United States might also have joined a general European trend of expansion that saw the eventual takeover of most of the world by European powers, primarily Britain. The Americans had followed the so-called Monroe Doctrine unofficially since the presidency of James Monroe, who declared the Americas the exclusive sphere of influence of the United States. This doctrine is seen as preceding Manifest Destiny and developed as a natural outgrowth of defending U.S. interests in the Western Hemisphere. By the end of the 19th century, rivalries developed with European powers, particularly Spain, because of historical interest in Cuba. In 1893, the United States intervened on the side of Western settlers and Westernized Hawaiians in overthrowing the Hawaiian monarchy. In 1898, the Spanish-American War launched a new period in American imperialism: Puerto Rico, the Philippines and Guam were annexed, and Cuba was occupied. These conquests, won with cooperation with local anti-Spanish rebels in some cases, came to define a missionary view where the United States was promoting the freedom and independence of subject peoples. Theodore Roosevelt became president in 1901 and later announced what is called the Roosevelt Corollary to the Monroe Doctrine, which explicitly promoted intervention over expansion in the Western Hemisphere.
Later, American domination of the international scene expanded when Woodrow Wilson promoted forming the League of Nations, which explicitly promoted Manifest Destiny in the context of promulgating democracy worldwide. The idea that America constituted an empire gained traction as it quashed rebellions in places like the Philippines and faced agitation for independence. American control of territory reached its maximum at the end of World War II with the conquest of Germany. But policies during the Cold War where the United States backed anti-Soviet regimes at the expense of local popular opinion generated a sense of empire. The consolidation of American holdings also allowed the United States to launch military operations in Cuba, Korea and Vietnam. The country became more isolationist following the devastating toll on American soldiers in Vietnam but is thought to have undergone an imperial revival under President Reagan who launched six invasions of South American countries and instituted an arming policy to drain the Soviet Union of financial resources in an arms race. American shipping of weapons to Iraq, Iran and Afghan rebels also saw the rise of American power in the Middle East.
The Persian Gulf War is seen as having been an American effort to protect its oil interests while having been promoted as an effort to protect Kuwaiti sovereignty. The Second Iraq War has been criticized as having been fought in the same context, while the 2001 invasion of Afghanistan and 2011 intervention in Libya are also said to be fought out of the interest of American energy and access to resources.
There is debate about using the terms empire and imperialism to describe American status or behavior. Some point to American cultural imperialism as pulling non-Western peoples and even Europeans away from their native cultural mores. There are also those who say the influence of the United States is in decline in the early 21st century because of a number of factors: alienation by and the lack of success of the war in Iraq, the declining value of the dollar, the increase of American debt, expansion of cultural competition from the Internet, the rise of the middle powers and China perhaps being a new superpower. The war in Iraq is seen as a major turning point by these scholars as having weakened American prestige, particularly financially. Others, like Fareed Zakaria, are reluctant to reach the conclusion the United States might go into decline like the British Empire did.