The deterioration of U.S.-Soviet scientific relations in 1946–1948 traditionally has been seen as simply a consequence of the growing political conflict between the United States and the Soviet Union. Scientific activities with direct military applications—most clearly manifested in the nuclear bomb—have been depicted as the primary motive for a variety of Cold War science policies, ranging from restrictions on international cooperation to the veil of secrecy placed over military-related scientific research. This article explores U.S.-Soviet relations in oncology in 1944–1948 and shows that science became an integral part and an instrument, rather than a mere reflection, of the Cold War confrontation. Science played a central role in the formulation of certain Cold War policies and informed Soviet decision-making on a wide range of policy issues that were essential to the growth of the Cold War. In this context, the symbolic value of science as a propaganda tool became no less important than its military applications.