Change in the Grand Strategy of the Republican Administrations of the United States, 1918-1988

The most fundamental orientation in the strategic culture of the United States of America is between the continuum of isolationism and internationalism. A comparison of the grand strategy of Wilson and Carter’s Democratic administrations, on the one hand, and the Harding and Reagan's Republican administrations, on the other hand shows that in the period between the beginning of World War I and the end of the Cold War, the Republican administrations-- unlike the Democratic administrations-- have shown major shift in their foreign policy strategy. As a result, the question arises as to why and how such a dramatic change had taken place? Accordingly, the objective of this paper is to investigate how system-level changes have led to a change in the foreign policy of Republican administrations by crossing the Republican Party sphere of influence? In order to answer this research question, the authors use the theoretical framework of neoclassical realism approach to foreign policy analysis. Given the stated objective of this study and considering that neoclassical realism theories use both the strength of international relations theories in the structural view of international phenomena, and the strength of theories of foreign policy by considering the internal and ideational factors, it seems that this theoretical framework is suitable for the present paper in order to provide insights into U.S. foreign policy-making.First, an overview of the history of US grand strategy and definitions of isolationism and internationalism in some of the most prominent scholarly works are presented. The proper conceptualization of the "degree of internationalism" as a dependent variable is offered. Then, using historical analysis and interpretation, the authors continue with a detailed study of the grand strategy of Republican administrations in five vital time periods      (i.e., World War I, World War II, the Korean War, the Vietnam War, and the Soviet occupation of Afghanistan), and examine the ups and downs of its degree of internationalism as compared to Democratic administrations. In each of these time periods, international changes affecting US vital interests, the reaction of senior Republican politicians to these changes, the resulting party controversies, and finally the impact they have had on the foreign policy of the Republican administrations have been analyzed in order to identify the main factors influencing the change in the grand strategy of these administrations. The reasons for the return of the Harding administration to the strategy of isolationism after World War I, the fracture within the Republican Party following the US entry into World War II, and its subsequent internationalist strategy, the Eisenhower administration’s policy towards the Korean War, the Nixon administration's response to the prolongation and erosion of the Vietnam War, and the differences in the foreign policy of the Carter and Reagan administrations in dealing with the Soviet occupation of Afghanistan are among the most important issues examined.The study of the procedures and processes of foreign policymaking indicates the existence of a coordination and order in the changes that have taken place. This  has manifested itself in the form of two different types of dynamics: The first is a steady line of change in the grand orientation of the U.S. foreign policy, which is gradually shifting from an isolationist strategy to an internationalist one. The second is an oscillation situation affected by the security-cost duality. Whenever a major security threat emerges, it tends to be more inclined to internationalism, and when the threat diminishes and the cost of internationalism increases, it tends to be less internationalist. At any rate, it is clear that the U.S. internationalism became more militant and interventionist after the Second World War.