<p>This thesis examines the Truman administration's non-use of nuclear weapons during the Korean War, June 1950 to January 1953. It investigates the entirety of the Truman administration's experience of the Korean War, rather than focusing on certain key periods. By examining official documentation, memoirs, newspaper reports, and information about public opinion, this thesis explains why the Truman administration chose not to utilise the atomic arsenal. It examines the opinions and influence of significant decision makers such as President Harry S. Truman, Secretary of State Dean Acheson, and Director of the Policy Planning Staff Paul H. Nitze. Truman, as president and ultimate decision maker, will be paid special attention, not least on account of his unique experience of having ordered the atomic attacks on Japan in 1945. This thesis also looks into the position of high-ranking military officers, such as General Omar N. Bradley, General Hoyt S. Vandenberg, and General Matthew B. Ridgway. In order to explain non-use, this thesis also investigates the influence of foreign allies and foreign opinion, particularly that expressed by the United Kingdom, the United States' most important ally. The role of public opinion within the United States is also considered. By examining in detail all of these factors and building a composite picture of the forces acting upon the administration, this thesis provides a more rounded and nuanced view of non-use by the Truman administration during the Korean War than that offered by the existing scholarship. It demonstrates that non-use was always a complex and problematic matter.</p>