This dissertation examines an increasingly common phenomenon in the post-Cold War context, the military coalition. At the heart of the dissertation is thus the question: what explains political leaders’ participation and burden-sharing decisions on military coalitions? In tackling the question, two distinct lines of research were brought together; the one based on alliances, the other based on foreign policy decision making. Based on the two lines of research, an explanatory framework was developed that combined the insights of alliance dependence thesis and poliheuristic theory. A set of hypotheses was derived and tested, utilizing a multimethod approach: statistical, case study, and experimental analyses. Overall, the results of applying the multimethod approach is suggestive of the strength of the poliheuristic theory, with a supporting role of alliance dependence thesis, in understanding participation and burden-sharing decisions on military coalitions. Moreover, though in large part the second Iraq War (2003 -) was used as the reference in much of the dissertation, an implicit underlying claim of the current research is that the findings may be extended to any broad context wherein the development of a military coalition may be a possibility.

This paper seeks to conduct a first test of the explanatory potential of the poliheuristic theory of foreign policy decision-making in the context of small states. The case studied is the Swedish decision to contribute to the UN-sanctioned and NATO-led Operation Unified Protector in 2011. The paper conducts a theory-testing Causal Process Tracing (CPT) study drawing on a variety of different sources including news articles, parliamentary records, government bills, official statements and remarks made by key individuals, and secondary sources. The result of the analysis demonstrate the potential validity of the poliheuristic understanding of the decision- making process operating in a small state, but fall short of demonstrating actual validity. The final results are thus more akin to results typically found in a plausibility probe case study, and future research is deemed merited based on the potential validity found.