The European Union (EU) has long been a destination for migrants seeking safety, stability, and better economic prospects. However, the significant increase in migration over the past decade—particularly during and after the 2015 refugee crisis—has introduced complex security challenges for EU member states. While migration itself is not inherently a security threat, the unprecedented volume and irregular nature of recent migration flows have strained administrative systems, fueled public anxiety, and occasionally been exploited by criminal and extremist networks. This essay examines the key security problems associated with large-scale migration to the EU, focusing on border control, terrorism, social cohesion, and policy coordination.