Sweden's decision to participate in Operation Inherent Resolve (OIR) in Iraq 2015 appears to be a paradox in the perspective of the new defence policy which emphasises an increased national defence capacity. The Swedish Armed Forces is expected to increase both its national capacity and its international commitments despite personnel and economical limitations?Besides this paradox the Swedish decision to participate in a US-lead operation appears to be a deviant case in several perspectives which has not been investigated by previous research. The Swedish Parliament decision is made in a security environment tinged by Russian aggression against Ukraine. At the same time the domestic situation is framed by a weak minority government which relies on unorthodox political agreements to survive. Despite its weak position the government abandons traditional practise like the operation´s legal framework, the processing of the government bill etc.The purpose of this thesis is to explain why Sweden seems to seek broader international military cooperation and deepening its international commitments when there is an increased need for national defence capacity-building.When Swedish security and sovereignty is threatened, directly by Russian aggression and indirectly by weakened international institutions it is a rational choice to seek broader and deeper cooperation with other partners. OIR is hereby a unique opportunity to an operational cooperation with the only state that alone can counteract Russian aggression in the Baltic region, USA.By a decision-making process with the ability to apprehend both foreign policy and defence policy ends the political opposition abandons ideological stands and political benefits enabling the parliament decision.