Since the end of the Cold War, Sweden’s security strategy has undergone radical changes. Due to recent years deteriorated security situation in Europe, the debate on Swedish NATO-membership has become more prominent. Previous research has mostly focused on the practical/military implications of the choice of security strategy whereas the knowledge about the political ideas and goals that are behind the choice of security strategy is largely unknow. Based on a qualitative approach, this thesis has studied how the Swedish foreign and security policy debate has changed between 1989–2018. Targeting the Social Democratic party, the Moderate Party, the Centre party and the Liberals, this thesis has described and analyzed these parties’ fundamental goals/values and world views from the perspectives of realism and liberalism. This study finds that there has been several changes both in world views and fundamental goals/values, where the earlier period in this study was more influenced by realism, to where liberalism started to become more prominent in the debate from the late 1990s until 2018, although realism has in some degree come back during recent years.