Between Hard and Soft Power: A Historical Analysis of U.S. Defense Diplomacy

Author

Shuhei Takahashi, Chapman UniversityFollow

Date of Award

Fall 12-2025

Document Type

Thesis

Degree Name

Master of Arts (MA)

Department

War, Diplomacy and Society

First Advisor

Mateo Jarquin

Second Advisor

Kyle Longley

Third Advisor

Minju Kwon

Abstract

In recent years, countries around the world—those of Europe but also Japan, China, and Russia—have accelerated their efforts to use military assets as instruments of diplomacy. This trend has contributed to the rising prevalence of the term “defense diplomacy” in national security discourse. The United States is no exception. Its abundant military assets and its global network of bases clearly demonstrate that it is the world’s leading practitioner of defense diplomacy. Yet the United States lacks a clear strategic document outlining the concept. Moreover, because existing definitions remain theoretically ambiguous and methods for assessing the effectiveness of defense diplomacy initiatives are underdeveloped, the topic has received limited attention from both academic and policy communities. In other words, the defense diplomacy debate rests upon an unstable conceptual foundation.

This study deconstructs the components of defense diplomacy drawn from existing scholarship and argues that its essence lies in the realm of soft power policy. Put simply, defense diplomacy refers to the use of military assets—primarily by defense institutions during peacetime —to generate soft power effects. Focusing on its soft-power dimension, this study seeks to establish a comprehensive understanding and analytical framework for defense diplomacy by proposing a new definition that clarifies its objectives, instruments, and actors.

Furthermore, this thesis traces the evolution of U.S. defense diplomacy along the broader trajectory of American foreign policy. This historical investigation reveals that, as the United States expanded its territory and ambitions, its military forces were increasingly tasked with roles that extended beyond their traditional missions. U.S. defense diplomacy emerged in earnest after World War II and reached its golden age during the Cold War. The overlap between the expansion of American ambition and the rise of defense diplomacy is no coincidence. Historical analysis shows that the soft-power effects of defense diplomacy at times served to conceal America’s ambition for global military primacy, thereby helping to legitimize its position as a superpower.

Long before Joseph Nye introduced the concept of “soft power” in 1990, the United States had already been attempting to transform its military assets into instruments of attraction. It appears to have achieved tangible results in such cases as the postwar occupation of Japan, the Cold War, and the war on terror in the Philippines. In the context of a new Cold War with China, defense diplomacy should be regarded as a policy instrument deserving of attention—just as soft power was in the 1990s.

Creative Commons License

This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

Recommended Citation

Takahashi, Shuhei. "Between Hard and Soft Power: A Historical Analysis of U.S. Defense Diplomacy." Master's thesis, Chapman University, 2025. https://doi.org/10.36837/chapman.000713