| dc.description.abstract | This thesis seeks to answer the question of why Sweden decided to apply for NATO membership in May 2022. To explain the decision, the analysis explores three hypotheses rooted in realism, liberalism, and institutional path dependence theory. The theories offer different explanations related to external threat, Sweden’s long-lasting tradition for military non-alignment, and the country’s pre-existing cooperation with NATO. The hypotheses are evaluated by combining the congruence method with process tracing, entailing the analysis of previous Swedish alignment decisions, and comparing them with the membership application of 2022. The study is based on data collected through document analysis and research interviews with Swedish experts and decisionmakers. The main findings suggest that Sweden applied for NATO membership because it perceived Russia as an increased threat and had few other alternatives due to its dependence on the alliance, incrementally magnified since entering the Partnership for Peace in 1994. Moreover, the aggressive behaviour of Russia was the most influential component in Sweden’s threat perception compared to observations of offensive capabilities. The results encourage future case studies and quantitative probes to explore the utility of operationalising threat in terms of aggressive behaviour when trying to explain alliance formation. They also encourage the mapping of states’ existing alignments for clues about the directions in which alliances will form if exposed to triggering events. | eng |