Since the founding of the North Atlantic Treaty Organization (NATO), US administrations have criticized their European allies for not meeting security burden-sharing goals. This study aims to gain insight into what factors motivate alliance members to contribute to the burden-sharing objectives they have agreed to achieve. From a US perspective, the need for its European allies to reach these goals will allow the United States to shift resources to more pressing strategic challenges like the rise of China. Informed by Mancur Olson's theory of collective action and Glenn Snyder's concept of the security dilemma in alliances, this project tests the hypothesis that the more a NATO ally's foreign policy interests align with those of the United States, the less that ally will spend on defense as a percentage of Gross Domestic Product (GDP). This study uses a mixed-methods approach. The primary metric measuring an ally's contribution is the percentage of its GDP spent on defense. Furthermore, this study breaks NATO's history into three geopolitical periods: the Cold War (1950 to 1990), the Post-Cold War (1991 to 2006), and the Resurgent period (2007 to 2019). The analysis yields robust support for the theory in periods lacking a major threat (i.e., the Post-Cold War). That means the more aligned an ally's foreign policy preferences are with the United States, the less that ally spends on defense as a percentage of its GDP in such periods. The implications of these findings suggest that with the intensified threat of Russia made apparent with its attack on Ukraine in 2022, burden sharing in the NATO alliance will be less of a problem for the US in the immediate future. However, when this threat recedes, the burden-sharing issue will return, and the United States will have to send credible signals (like withdrawing troops from Europe) to its allies to cause them to question US protection and increase defense spending.


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Graduation Date





Mousseau, Michael


Doctor of Philosophy (Ph.D.)


College of Sciences


School of Politics, Security and International Affairs

Degree Program

Security Studies




CFE0009407; DP0027130





Release Date

December 2022

Length of Campus-only Access


Access Status

Doctoral Dissertation (Open Access)