It is commonly assumed that the EU member states share a single interest in the external borders. However, we emphasize that the EU is characterized by a spatial territorial paradigm, as the creation of a common area of mobility constitutes centre and periphery within the EU. The difference between centre and periphery can be attributed to the unequal distribution of benefits and costs for maintaining the Schengen area among EU member states. Hence, the question emerges how it is possible that the tension between centre and periphery does not lead to the breaking up of the Schengen Area. It is argued that mutual trust was a prerequisite for the implementation of the Schengen Area, but with the increase in heterogeneity between the Member States in the course of eastern enlargement, the decrease of trust in the soon-to-be new member increased the fragility of the Schengen Area. Consequently, the question becomes apparent how the Schengen area is stabilized and consolidated despite the lack of trust among member states. Supranationalization, as it is further argued, serves as a functional equivalent for trust, as it reduces the periphery's discretion in policing the external borders and thereby enhances the centre's stable expectations in the border's control performance, while exterritorialization of migration control reduces the burden for the peripheral member states.
