This article examines the enunciation in March 1947 of the Truman Doctrine. The doctrine pledged the United States to “assist free peoples who are resisting attempted subjugation by armed minorities or by outside pressures.” Although the statement was initially aimed at winning congressional support for U.S. aid to Greece and Turkey, where the administration feared Soviet penetration, it ultimately underpinned U.S. Cold War policy throughout Europe and around the world. Moreover, the doctrine addressed a broader cultural insecurity regarding modern life in a globalized world. The administration's concern over communism's domino effect, its media-sensitive presentation of the doctrine, and its mobilization of U.S. economic and military power to modernize unstable regions marked the advent of a modern U.S. foreign policy. In its maintenance of military preponderance, its nation-building activities, its organization of alliances, its advocacy of “regime change,” and its resort at times to limited war against armed insurgencies, the Truman Doctrine foreshadowed the contemporary Bush Doctrine against international terrorism.