Summary Estonia, Latvia, and Lithuania have experienced continuous threats from the Russian Federation throughout their history, including loss of independence and occupation. These countries’ fears of Moscow’s aggressive policy escalated again when Russia launched its aggression in Ukraine, seeking full subordination to Moscow. These events did not come as a surprise to the three Baltic states, which had been warning against Russia’s aggressive policy for many years. The article reviews the political decisions and support for Ukraine in its struggle to restore sovereignty. It examines the perception of security of these countries and the evolution of threat assessments, as well as the development of defense capabilities and the strengthening of the resilience of societies. The article aims to review the state of security in the Baltic states in the context of the Russian aggression in Ukraine and to assess the threats and decisions taken to increase security. The findings are based on a study of documents, as well as on an overview and analysis of existing literature and sources. The case study methodology in relation to Estonia, Lithuania, and Latvia allows the implementation of comparative analysis.