This article discusses Russia's annexation of Crimea and its security implications for the Baltic States. The study exclusively examines two considerable impacts of the Russian annexation of Crimea, in term of its Compatriots and Hybrid warfare strategies on the security of the three Baltic States (Estonia, Latvia, and Lithuania) through qualitative and descriptive analysis. It discusses Russia's Compatriot policy which was behind this annexation, and how this policy is an essential tool of the Kremlin against the Baltic States using their large portion of the population comprised of ethnic Russians. The paper finds that Russia annexed Crimea due to its geostrategic importance. Each of the three Baltic States also has strategic significance for the Russian Federation. In this sense, Russia's aggressive policies are becoming a great challenge for the security of the three States. This instant study highlights the security implications of the Russian annexation of Crimea for the Baltic States in a descriptive-analytical way.