There are a great number of analyses on United States foreign policy, but among all of them there is a specific kind that uses a distinction between realist and idealist polices to classify it. The present dissertation engages itself with this specific kind of analysis, proposing an alternative to this realist-idealist interpretation. Recalling the concept of the liberal tradition of the United States, first developed by the followers of the consensus history paradigm during the decade of 50, this work identifies the influences of this liberal tradition on United States foreign policy. In accordance with the argument of the liberal tradition, the major characteristic of politics in the United States is the absence of a conservative tradition; the liberal values are completely embedded on the political thought of the country. The great reflex of this fact on foreign policy is the capacity of the United States in projecting its own interests and values as if they were universals. This characteristic supplants the supposed realist-idealist division of foreign policy. In this way, this work develops an analysis of the relations between the writings on foreign policy that use this realist-idealist division and the liberal tradition, in two specific moments: the end of World War II, at the time when this distinction starts to spread, and at the end of Cold War.