The article analyses the main mechanisms of developing Germany’s security strategy in the context of key issues and prospective threats to European security in the 21st century. By examining changes in the overall security landscape and contemporary challenges to the global order, it analyzes how countries’ military security strategies shape approaches to defence and protection over a certain historical period. On the other hand, a detailed analysis of the prerequisites and course of military conflicts at the end of the 20th and the first decades of the 21st century allows the conclusion that those states capable of swiftly and effectively altering their approaches to security are able to resist external threats efficiently. To achieve this, a state must possess and continuously refine all doctrinal documents related to national defence matters. The German doctrinal documents regarding the definition of national security fundamentals are specifically studied. This is pertinent for understanding shifts in the views of the senior military and political leadership on how to adequately ensure the state’s integrity from external and internal threats. The article asserts that Germany’s leadership pays significant attention to general security issues, including purely military aspects. Moreover, such shifts in perspectives occur under changes in the global military-political environment, not only in Europe but worldwide. At the same time, the article examines the main sections of the latest National Security Strategy of Germany, which was approved in 2023. According to this document, one of Germany’s primary tasks today is direct participation in shaping a free international order committed to international law, the United Nations Charter, and sovereign equality of states. Therefore, emphasis is placed on the fact that such an approach to national security issues and Germany’s NATO membership are bases for providing significant military-technical assistance to Ukraine in countering Russian aggression.