An important part of American exceptionalism is the belief that liberal democracy will work everywhere; in other words, limited government, freedom of the press, checks and balances, due process, etc. are, and should be, universal. That doctrine has a really poor track record in many parts of the world, most recently in the Middle East, but we expose ourselves to charges of hypocrisy if we don’t adhere to it. As a result, our imperialist efforts in the recent past have typically focused on replacing tyrants with more acceptably democratic leaders, not on taking and exploiting territory, and our political arrangements typically run afoul of the local political culture and therefore collapse after we leave.