The paper is devoted to assessing the impact of migration trends on the national security of Ukraine. The history of the formation of the population of Ukraine, population migration trends on the eve of the large-scale invasion of Russian troops, including the features of external labor and educational migration, immigration to Ukraine, intrastate migration movements, the impact of various components of the migration movement on national security, have been studied. Particular attention is paid to the changes in the migration situation after February 24, 2022 and the challenges to the national security of the country in modern conditions. The relevance of the study is due to the presence of a number of threats to the national security of Ukraine in the context of an unfavorable migration situation in 2014-2021 and unprecedented, the largest since the Second World War, the scale of forced migrations in Ukraine, formed after a large-scale invasion. The purpose of the study is to identify migration threats to national security and develop recommendations for their mitigation. Methods of abstract-logical, systematic approach, expert assessments, method of complex use of information from various sources are used. The cyclic interdependence of migration processes and components of national security is revealed. In particular, it is shown that unfavorable migration trends cause an increase in negative processes affecting national security, which, in turn, enhances the negative trends in population migration. It is shown that the role of migration in ensuring national security, being significant even before the large-scale invasion of Russian troops, is sharply increasing in modern conditions. Recommendations for adjusting the migration policy in the conditions of war and post-war reconstruction of the country are proposed.