<P> However, historian Donald W. Meinig says the imperial behavior by the United States dates at least to the Louisiana Purchase, which he describes as an "imperial acquisition--imperial in the sense of the aggressive encroachment of one people upon the territory of another, resulting in the subjugation of that people to alien rule ." The U.S. policies towards the Native Americans he said were "designed to remold them into a people more appropriately conformed to imperial desires ." </P> <P> Writers and academics of the early 20th century, like Charles A. Beard, in support of non-interventionism (sometimes referred to as "isolationism"), discussed American policy as being driven by self - interested expansionism going back as far as the writing of the Constitution . Some politicians today do not agree . Pat Buchanan claims that the modern United States' drive to empire is "far removed from what the Founding Fathers had intended the young Republic to become ." </P> <P> Andrew Bacevich argues that the U.S. did not fundamentally change its foreign policy after the Cold War, and remains focused on an effort to expand its control across the world . As the surviving superpower at the end of the Cold War, the U.S. could focus its assets in new directions, the future being "up for grabs" according to former Under Secretary of Defense for Policy Paul Wolfowitz in 1991 . Head of the Olin Institute for Strategic Studies at Harvard University, Stephen Peter Rosen, maintains: </P> <P> A political unit that has overwhelming superiority in military power, and uses that power to influence the internal behavior of other states, is called an empire . Because the United States does not seek to control territory or govern the overseas citizens of the empire, we are an indirect empire, to be sure, but an empire nonetheless . If this is correct, our goal is not combating a rival, but maintaining our imperial position, and maintaining imperial order . </P>

When does the united states become an imperial power