The role of hegemon policies and external threat in NATO's burden sharing: The example of the Ukraine war

Similar to many other international organizations in which states are a part of, being a member of NATO also has some benefits and costs. While the benefits of this membership are generally shared equally, the costs are not always borne at the same rate, which leads to the problem of burden sharing. This thesis examines this burden sharing through defense expenditures and investigates the underlying reasons for their differences. The thesis focuses on the Ukraine - Russia War process, which has been going on for about ten years, by using case study and process tracing methods. Based on the hegemonic stability and external threat theories, the effects of three independent variables, namely aggressive intentions (Russia), the strategy of the hegemon (USA) and the size of the hegemon, on burden sharing were tested. As a result of the analysis, first of all, the possible benefits of using these two theories together were revealed. In addition, it was concluded that in burden sharing; hegemonic policies and external threats were effective together by balancing each other during the Obama period, while hegemonic pressures during the Trump period and increasing Russian aggression during the Biden period were the main determinants. Moreover, the increase in defense spending of NATO members (excluding the US) during the Biden administiration, which exceeded previous periods, has been an indication that external threats are more effective than hegemonic pressures in burden sharing.