This thesis examined Sweden’s signing of the host country agreement with NATO in year 2014, which has been a subject to criticism mainly due to its constraining effect of Sweden’s principle of non-alignment. The power of balance theory by Kenneth Waltz has been applied to understand this change in Swedish security policy. The methodology of this thesis is a qualitative analysis with a deductive approach. The empirical materials consist of the Swedish government’s official investigations, the Swedish parliaments protocol, the People and Defence National Conference of the Swedish government offices and a direct report of the Defence Committee's security policy report. The purpose of this thesis was to identify why the Swedish government decided to sign a host country agreement with NATO in the particular year of 2014. Thus, the purpose of this thesis was to find an explanation based on a theoretical framework for why this change in Swedish security policy has occurred. The result has shown that the change in Swedish security policy has taken place in relation to shifts in power dynamics in the international system and factors such as the own states circumstances for choosing a security strategy. Sweden’s signing of the host country agreement is a security strategy described as a risk diversification strategy. In which the Swedish government creates a network of multi- and bilateral defence co-operation to reduce the imbalance between its own country's military power and the shifts of power in the international system.