This thesis aims to explain how small states, in this case Sweden, security politics adapts to new circumstances after great conflicts in the 20^th century. The analytical model is built by a combination of the opposite theories of international politics, realism and idealism, combined with actor based and structure based perspectives and thus creating a four field analytical matrix.

The empirical foundation constitutes of three post conflict periods; post-first world war, post-second world war and post-cold war periods. For every period three cases are analyzed; one foreign politics initiative, one association to an international organization and one defence politics decision. In the post-first world war period the focus is on the Swedish intervention of the Åland archipelago, the association to the League of Nations and disarmament decision in 1925. In the post-second world war period the focus is on the association of Sweden to the United Nations, the Swedish initiative to a Scandinavian defence alliance and the defence decision of 1948. In the post-cold war period the focus is on the Swedish association to the European Union, the Swedish participation in the NATO led IFOR operation in Bosnia and the defence decision in 1996.

The main conclusions of these investigations are that small states, like Sweden, both are restricted in their foreign and security politics by international structures and able to use the same structure to promote their interests. Time is a key element for analyzing both structural and actor based aspects of a small states capacity. Also, in the case of Sweden, there tends to be a tension between an idealistic dominated politics and a realistic dominated politics when it comes to foreign and security politics, and that idealism seems to have increased in the latter period.