America no longer has a national consensus on the superiority of Western civilization. But we do espouse something the British didn't. As a nation of immigrants, we declare that anyone from any corner of the globe has the ability to practice democracy if only given the chance. It may be that we don't really believe this, that it is just a piety. Americans may secretly believe, as most Europeans seem to, that living democratically is a question of having the right civilization, and that Africans and people in the Balkans don't have it.
But if Americans do believe that all people are endowed by their creator with democratic rights and abilities, and if we are right, then a form of colonialism may be sustainable -- one that goes into some of the places where authority has broken down and imposes order long enough to allow the locals to govern themselves. It would be a colonialism that restrains its moralistic and improving impulses.