Chapter 4 focuses on the EU–Turkey Syrian refugee deal, which was activated on November 29, 2015. It makes the argument that Turkey used the urgency of the refugee crisis and its position as a major transit country for refugees en route to Europe as leverage to acquire visa liberalization with the EU and bring momentum to its accession negotiation talks. By using active diplomacy and issue-linkage bargaining, Turkey was also able to secure the EU’s commitment to modernization of the Customs Union Agreement and provision of financial support for the welfare and protection of Syrian refugees in Turkey. Upon realizing that the perquisites secured through the deal were not going to materialize due to a multiplicity of reasons, Turkey switched to compellent threats and blackmail and engaged in boundary challenging against the EU. The refugee deal between the EU and Turkey makes it very costly for the EU to ‘lose’ Turkey and will serve as a good litmus test on whether Turkey will switch from challenging to breaking its boundaries with the EU. If the threat of revoking the deal becomes reasonably credible, then it is possible to talk about a switch to boundary breaking.