"American Exceptionalism" is the idea that America is in a class by itself, above and beyond other nations. There's something inherently prejudicial about such a view of one's own nation, believing that all others are lesser. And since America, during the time frame of imperial expansion, was a predominantly white nation, claiming "exceptionalism" also carries an implied racist tinge.
As the US expanded overseas, racial prejudice was shown especially in how the Filipinos were viewed as the US took over control of the Philippines in 1898 and then waged war against the local population to maintain control of the country.
