No country has been more closely associated with the practice and ideology of “the liberal peace” than the United States. Indeed, the prominence of the concept is in major part the result of America's rise to global power. As this article sets out, the ideological history of the United States has wedded it to a brand of internationalism that rests for its integrity, in American eyes, on the pursuit of liberal universalism. Those who favour interventionist solutions to conflicts within and between states must make their peace with this characteristic of US political culture or they risk attacking the political basis for significant US international engagement of any kind. Given the absolute necessity of American involvement for the success of any regime of global interventionism, the latter would be a move of dubious wisdom.