European defence integration has risen to become one of the most central debates in the European Union. Debates on European defence integration involve European strategic autonomy, an ambiguous concept with different understandings in which are debated both politically and academically. By applying the theories of neofunctionalism and Liberal Intergovernmentalism, the thesis aims to highlight supranational and intergovernmental drivers of European defence integration. In doing so, it can provide a foundation to understand the concept of European strategic autonomy. Although previous research has not yet analysed European defence integration through theories with rivalling perspectives, it shows that studying both supranationalism and intergovernmentalism in European defence is important, since the relationship between supranationalism and intergovernmentalism is puzzling. Thus, this thesis analyses the case of the Strategic Compass for security and defence, since it is closely connected to both European defence integration and European strategic autonomy. A qualitative content analysis of the Strategic Compass is conducted to address the gap in previous research. The results show that there is an embeddedness within European defence integration, with coexisting supranationalism and intergovernmentalism. The European Commission has managed to gain influence in European defence, and the results show that it may stem from common interests, both from Member States and EU-institutions. This enables theoretical explanations for understanding European strategic autonomy in two separate ways.