<P> One of the earliest historians of American Empire, William Appleman Williams, wrote, "The routine lust for land, markets or security became justifications for noble rhetoric about prosperity, liberty and security ." </P> <P> Max Boot defends U.S. imperialism by claiming: "U.S. imperialism has been the greatest force for good in the world during the past century . It has defeated communism and Nazism and has intervened against the Taliban and Serbian ethnic cleansing ." Boot used "imperialism" to describe United States policy, not only in the early 20th century but "since at least 1803". This embrace of empire is made by other neoconservatives, including British historian Paul Johnson, and writers Dinesh D'Souza and Mark Steyn . It is also made by some liberal hawks, such as political scientist Zbigniew Brzezinski and Michael Ignatieff . </P> <P> British historian Niall Ferguson argues that the United States is an empire and believes that this is a good thing: "What is not allowed is to say that the United States is an empire and that this might not be wholly bad ." Ferguson has drawn parallels between the British Empire and the imperial role of the United States in the late 20th and early 21st centuries, though he describes the United States' political and social structures as more like those of the Roman Empire than of the British . Ferguson argues that all of these empires have had both positive and negative aspects, but that the positive aspects of the U.S. empire will, if it learns from history and its mistakes, greatly outweigh its negative aspects . </P> <P> Another point of view implies that United States expansion overseas has indeed been imperialistic, but that this imperialism is only a temporary phenomenon; a corruption of American ideals or the relic of a past historical era . Historian Samuel Flagg Bemis argues that Spanish--American War expansionism was a short - lived imperialistic impulse and "a great aberration in American history", a very different form of territorial growth than that of earlier American history . Historian Walter LaFeber sees the Spanish--American War expansionism not as an aberration, but as a culmination of United States expansion westward . </P>

In what ways has the united states practiced imperialism