The author argues that the membership in a larger alliance has particular consequences for the defence cooperation between member states. For that purpose, the study examines Sweden’s application for NATO membership and its impact on German-Swedish defence cooperation. The study uses current research on differentiated integration and minilateralism as a starting point to frame the object of research. Influencing factors that either limit, enable, or promote minilateral defence cooperations are theoretically identified and empirically verified. The subject’s topicality makes expert interviews on ministry-, department-, and forces headquarters level the suitable empirical foundation. The author further argues that the complexity of the problem requires an eclectic approach to answer the research question. For this purpose, minilateral defence cooperations are defined as regimes and linked to the realistic, liberal, and constructivist interpretation of regime theory. The study finds that relative gains, absolute gains, and normative factors can explain changing preconditions under which German-Swedish defence cooperation is likely to increase in the face of Sweden’s NATO membership.

Uppsatsens syfte är att förstå hur den Europeiska kommissionen och Europaparlamentet diskuterar differentierad integration. Metoden som används är en kvalitativ textanalys där teorier om europeisk integration från forskningsområdet internationella relationer används som analysverktyg. En slutsats som dras är att teorierna om neofunktionalism och liberal intergovernmentalism kan komplettera varandra för att ge en mer mångsidig förståelse av de något olika diskussionerna. Den Europeiska kommissionen och Europaparlamentet vill i de tolkade dokumenten främst bibehålla en enhetlig union, men de är villiga att ge frihet till ambitiösa medlemsstater inom särskilda policyområden genom inkluderande opt in-lösningar av differentierad integration. Den Europeiska kommissionen och Europaparlamentet är motståndare till exkluderande opt out-lösningar av differentierad integration, de menar att exkluderande former av differentiering exempelvis skulle kunna leda till polarisering, fragmentering och ett upplevt skapande av ett första- och andraklassens EU-medlemskap. Gradvist tillträde är därmed historiskt sett som en sämre lösning till problemet kring kandidatländers integration, om gradvist tillträde skulle implementeras i integrationsprocessen för framtida kandidatländer skulle det därmed innebära ett trendbrott inom utvidgningspolicyn från den Europeiska unionen. / The thesis’ purpose is to understand how the European Commission and the European Parliament discusses differentiated integration. The method applied is a qualitative text analysis in which theories of European integration from the research field of international relations is used as an analytical tool. One conclusion recognises the fact that both the theory of neofunctionalism and liberal intergovernmentalism are complementary tools in understanding the discussions from a multitude of perspectives. The European Commission and the European Parliament expressed in the analysed documents that uniform integration within the Union is preferred, but they are still open to giving freedom to Member States in specific policy areas through inclusionary opt-in measures of differentiated integration. The European Commission and European Parliament are opposed to exclusionary opt-out measures of differentiation, as they mean it could lead to polarisation, fragmentation, and the perceived notion of first- and second-class Member States. Staged accession is therefore historically seen as a poor solution to the problem of integrating the candidate countries, if staged accession would be implemented into the integration process for future candidate countries, it would therefore mark a change in trend within the enlargement policy of the European Union.