The U.S. emerged from World War II as the world's leading scientific and technological nation, consolidating its advantage for the next two or three decades. This paper describes how the State Department used the nation's dominance in the nuclear field, inherited from the Manhattan Project, to divert the resources of Western European states, notably France and Germany, into a civilian nuclear power program undertaken by a new supranational organization, Euratom. The determination on the continent to re-launch the European integration process in 1955, the Suez crisis in 1956, and the launch of the Sputniks in 1957 were opportunities ably exploited by officers in the State Department to use America's scientific, technological, and industrial depth in nuclear power as a political weapon. To this end they withheld the supply of enriched uranium for as long as possible from nations that wanted the fuel through bilateral agreements with the Atomic Energy Commission. In parallel they offered nuclear materials and know how, along with economic and political incentives, to encourage nations to commit to Euratom. This policy was strongly opposed by senior officials in the AEC and in the fledgling International Atomic Energy Agency, as well in Britain and in some continental countries, but to no avail. Though the State Department's efforts eventually bore little fruit, the paper clearly shows how U.S. leadership in science and technology was mobilized to promote America's foreign policy agenda in Western Europe in the early Cold War.