The paper contributes to the question of the applicability of international legal principles regarding the prohibition of the use of force and the right to self-defense to non-state actors from a distinctly continental European perspective, based on a constitutional understanding of the United Nations Charter. Three central themes are addressed: preventive self-defense, the question of whether non-state actors can be considered aggressors in the sense of Article 51 of the United Nations Charter, and the conditions for attributing an armed attack to a state as a prerequisite for self-defense measures against that state. A potentially changing understanding of Article 51 of the United Nations Charter, which would regard non-state actors as aggressors, is ultimately viewed with skepticism.