The purpose of this article is to explain the history, sources and variations relating to the grand strategy of United States with regard to international security. In particular, it argues that there is a strategy which defines the interests and values that the US governments must defend, regardless of their ideological positions, which can be principally understood in terms of their beliefs on defensive and offensive realism, as well as exemplary liberalism and crusade liberalism. Rather than being conceived as theoretical or analytical stances, these variations of American realism and liberalism are seen as doctrines which have been developing historically since independence. Given that this grand strategy constitutes an institutional framework which is difficult to avoid, the paper explains, through the use of examples, the way in which the governments under George W. Bush Jr. and Barack H. Obama appropriated this strategy.