I have what I think is a perceptive quote from Tony Judt, reviewing Joseph S. Nye Jr.'s The paradox of American power in the New York Review of Books, vol XLIX, no. 13 of 15 August 2002:
What gives America its formidable international influence is not its unequaled capacity for war but the trust of others in its good intentions. That is why Washington's opposition to the International Criminal Court does so much damage. It suggests that the US does not trust the rest of the world to treat Americans fairly. But if America displays a lack of trust in others, the time may come when they will return the compliment.
All I'd say in addition is that the concept of noblesse oblige is pertinent. As the world's great superpower, the US has a responsibility to behave well, and be seen to do so. (Full text of Judt's essay.)
Finally, a less serious take on American politics.