The migration crisis at the eastern border of the EU has become a key challenge for member states such as Poland and Finland. The aim of this thesis is to describe the instrumentalization of migration by third countries such as Belarus and Russia, which use migrants to exert political pressure on the EU. The case study of Poland and Finland allows for a comparison of two different approaches in terms of border management policies. In Poland, in response to the influx of migrants, strict border protection measures were introduced. Finland otherwise introduced enhanced cooperation mechanisms with NATO and Frontex to better counter the migration crisis. Both countries have recognized that migration can be used to disrupt internal stability, which is related to the hybrid threats. The actions targeting weaker points in the security system of states that are difficult to neutralize by conventional means as a combination of migratory pressures with other elements, such as disinformation, cyberattacks on public institutions, and attempts to create social tensions in destination countries, challenged EU security. The case study of Poland and Finland reveals differences in approaches to border protection and international cooperation. Poland, focusing on physical border protection, while Finland has focused on legislative and operational management of migration in the face of hybrid threats. The paper uses qualitative research methods based on available scientific sources relating to the theoretical and practical dimensions of the issue and discusses the impact of migration on the security of the EU.