An excerpt from William Appleman Williams' 1961 The Contours of American History over at the Verso blog:
Relieved and exhilarated by their triumph over the Axis Powers in 1945, Americans seemed to have assumed that their traditional dream of becoming a world unto themselves was about to be realized. Far from having become disillusioned (or isolationist), they appeared casually confident that their earlier visions of Manifest Destiny were materializing as the reality of the present. Though vaguely uneasy about the full extent of its powers, most Americans looked upon the atom bomb as a self-starting magic lamp; even without being rubbed it would produce their long-sought City on the Hill in the form of a de facto American Century embracing the globe.
It was generally taken for granted that such benevolent Americanization of the world would bring peace and plenty without the moral embarrassments and administrative distractions of old-fashioned empires. And so, having created the most irrational weapon known to man, Americans proceeded with startling rationality to abandon the mass army as their principal strategic weapon. Armed only with their bomb, they then generously offered to help everyone become more like themselves. “We are willing to help people who believe the way we do,” explained Secretary of State Dean Acheson, “to continue to live the way they want to live.”
Had Americans applied their intelligence, humanitarianism, and power to the paradox of plenty without purpose within their own society and to the needs and aspirations of their fellow humans throughout the world, it is possible that their self-centered dream would have been transformed into a vision of brotherhood among men.
More here.