This article examines the role of the Baltic Sea Region Border Control Cooperation (BSRBCC) which was founded on a 'soft-law' instrument in the Baltic Sea region. It does this in relation to the developments in the European Union (EU), including the extensive supranational EU rules on border management and the European Agency for the Management of Operational Cooperation at the External Borders (Frontex). Border management is related to core national interests and guarded by states, which has an impact on the relationship between the different regulatory layers and the implementation of the provisions in question at different levels; national, sub-regional and regional. The national level is still 'strong' in the domain of border management. This explains both tensions in the relationship between the supranational and national levels and in the implementation of the provisions in question, as well as the weak legal status of the BSRBCC. Several 'safeguards' for national competences in the EU treaties constitute restraints that will prevent the EU from entirely exercising its power to develop a common policy on border control. Nevertheless, Frontex's mandate has been enlarged extensively in the latest 2016 Frontex Regulation, but concerns about losing national sovereignty due to the new and enhanced role of Frontex still seem groundless. Under normal circumstances, it seems unlikely that Frontex would act against the will of a member state, but it remains to be seen how the new Frontex mandate will unfold. In practice, the fact that the BSRBCC is founded on 'soft-law' instruments rather than legally binding international agreements has not been an obstacle to the Frontex-BSRBCC cooperation. There is a solid mandate in the 2016 Frontex Regulation for its continued support through national authorities for key BSRBCC activities, such as building capacity by establishing best practices, and providing training. The border cooperation in the Baltic Sea within the BSRBCC seems to have adapted well to the changing EU and Schengen contexts. The cooperation seems, despite its legally weak status, to be of added value for the national authorities that participate, not least as Russia, a crucial partner in the Baltic Sea region context, takes part in it, but also because of its possibilities to provide for a more enhanced and closer sub-regional cooperation. Seemingly, the BSRBCC complements the EU in the domain border management. The cooperation between national authorities in the Baltic Sea has no equivalence in any other comparable 'sea cooperation' by EU member states. The geographical and legal aspects taken together make it unique; almost only EU member states, bound by the same EU legislation, border the semi-enclosed Baltic Sea and are participants in the BSRBCC.