The idea that the United States is bequeathed the special mission of leading mankind toward liberty has dominated U.S. foreign relations since the American Revolution. It remains the most pervasive theme in Americans' thought about the world to the extent that over time, it has become firmly embedded in the nation's historical and cultural consciousness. A study of diplomatic, intellectual, and cultural history, America in the World: Ideology and U.S. Foreign Policy, 1944-1950 examines the impact of this exceptionalist vision on the policies and public debates that influenced Americans' thinking about their role in the world from the beginning of their efforts to design the global post-World War II order to the outbreak of the Korean War in 1950. Believers in Lockean progress and advocates of modernization, the administrations of Franklin Roosevelt and Harry Truman sought to establish a one-world order based on American liberal political and economic ideals. At the heart of this American-designed postwar world stood the United Nations, created to ensure collective security and foster a spirit of international collaboration, and transnational institutions like the World Bank and the International Monetary Fund, envisioned to protect the global economy and promote free trade. These institutions served as concrete articulations of U.S. national interests yet at the same time they were intended to inaugurate a "New Deal" and a "Fair Deal" for the world. Interpreting American post-war and Cold War policymaking through the lens of exceptionalism provides a complementary methodological framework to the national security or economic theses more commonly employed to describe this period. When the Soviet Union refused to accept the American-designed one-world order, the American response - inside and outside of government - was overwhelmingly shaped by ideology. While economic considerations and national security influenced U.S. Cold War policy, this dissertation demonstrates that it was the challenge posed by Moscow's universalist aspirations and Communism's inherent teleological ideology that caused Americans to turn the Cold War into a battle for a way of life.

Strategic upheavals, such as the emergence or disappearance of geopolitical threats or radical technological changes, generate profound uncertainty and intense debate about a state’s future strategy. How do decisionmakers reexamine and revise strategy amidst these upheavals? Existing theories of strategic change recognize the significance of upheavals, but raise questions about the mechanisms by which decisionmakers embrace or discard new ideas about strategy. contend that understanding strategic change requires attention to narratives––stories about the past and present of international politics that suggest legitimate pathways for future action. I develop a theory of narrative emergence, positing that after upheavals, national security elites compete to mobilize support for their vision of future policy. They use public and private debates to legitimate their positions and build domestic coalitions. I identify four rhetorical strategies––persuasion, rhetorical coercion, co-optation, and transgression––that have different effects in mobilizing or demobilizing coalitions. If one coalition builds cross-cutting support, this can entrench their rhetoric in public discourse over time as part of a dominant narrative that shapes subsequent strategy debates through constraining and enabling effects. I evaluate this theory in the context of two cases of strategic upheaval in the United States, focusing on the puzzles of U.S. nuclear strategy: the arrival of the atomic age and the achievement of strategic parity between the U.S. and Soviet nuclear arsenals. In the first case, I use qualitative and text analysis to track the rise of a dominant narrative about nuclear weapons during the early Cold War. In this contradictory narrative which I label “Waging Deterrence,” the bomb was both an unusable, revolutionary deterrent and an essential tool for fighting and winning the next war. I draw on archival sources to trace the emergence of this narrative during the Truman and Eisenhower administrations, showing this narrative was not predetermined, but contingent on domestic debates as speakers––Presidents, civilian advisors, military elites, and others––used rhetorical strategies in public and private to co-opt and silence opponents. This narrative constrained the possibilities for strategic revision during the later Eisenhower and Kennedy administrations. In the second case, parity’s mutual vulnerability upended this narrative; narratives remained unsettled until the Carter administration, where domestic legitimation contests facilitated the return of Waging Deterrence to justify competitive nuclear postures that had a lasting impact on U.S. nuclear strategy. The project offers a novel mechanism to understand strategic change and highlights the discursive and domestic politics of nuclear strategy, showing that foundational U.S. deterrence concepts emerged in part from domestic legitimation contests that rendered other options illegitimate. It also offers insights into policy debates about the future of nuclear and grand strategy amidst contemporary upheavals, suggesting contested processes of narrative construction will be central to shaping future strategy.

This work examines the actions of the Joint Chiefs of Staff during the first year of the Korean War. Officially created in 1947, the Joint Chiefs saw their first true test as an institution during the conflict. At various times, the members of the JCS failed to issue direct orders to their subordinate, resulting in a divide between the wishes of President Truman and General MacArthur over the conduct of the war. By analyzing the interaction between the Joint Chiefs and General Douglas MacArthur, the flaws of both the individual Chiefs as well as the organization as a whole become apparent. The tactical and strategic decisions faced by the JCS are framed within the three main stages of the Korean War.