Migration, as a challenge to be considered at the level of the North Atlantic Alliance, appeared in the Strategic Concept of the Alliance only in 2022. Nevertheless, in the 21st century, especially since 2015, the problem was raised at all NATO summits and expressed in expectations towards the Alliance, especially by southern and eastern member states experiencing intense, though different, problems generated by international population movements caused by armed conflicts or socio-economic and environmental factors occurring in the countries – sources of immigration. On the one hand, NATO’s involvement in both the Mediterranean basin and in supporting the protection of the border on the eastern flank of the Alliance is, a response to the expectations of member states in terms of ensuring their security, but on the other hand – in a broader sense – it is proof of the evolving nature of the Alliance, reacting to the developments in the area of security and confirmation of the will to be more involved in the non-military field, even if such activity results in accusations of securitization of migration.