Abstract: The subject of the article is the process of forming the CERN sanctions regime regarding Russia's participation in global scientific megaprojects in the field of theoretical physics. The purpose of the article is to reveal the content and organizational mechanism of CERN sanctions aimed at ending institutional cooperation with Russia. The objectives of the study include determining the algorithm of the long-term bilateral strategic partnership between Russia and CERN; revealing the grounds and logic of CERN's unilateral termination of promising cooperation with Russia, as well as predicting the negative consequences of sanctions. The authors pay special attention to testing the research hypothesis that CERN's anti–Russian sanctions policy is based on a combination of, on the one hand, politicized principles, and, on the other, extreme prudence, which resulted in the "stretching" of the measures taken over time and their focus on taking into account the current geopolitical situation. This indicates the incompleteness of the transition from the logic of scientific diplomacy to the rigid logic of sanctions, which makes it possible to predict the preservation of some elements of scientific diplomacy in relations between CERN and Russia. The methodological base of the research includes traditional methods and approaches (analysis and synthesis, abstraction and generalization; modeling; forecasting; the general scientific principle of dialectical development; a systematic approach), as well as new methods (meta-analysis, discursive analysis, stochastic factor analysis). It is concluded that CERN's sanctions policy, based on an appeal to value motivations, is characterized by flexible consideration of the current geopolitical situation and the gradual nature of the restrictive measures taken. The research hypothesis about the preservation of a certain potential of scientific diplomacy in relations between CERN and Russia has been confirmed in the work. This is reflected in the continuation of cooperation and fulfillment of obligations under existing bilateral agreements. It is proved that, by their nature, CERN sanctions belong to an independent category of sanctions against Russian science, which are imposed by international structures operating in the field of megascience. The novelty of the research lies in the actualization of the need to develop a special direction of Russian scientific and technical policy aimed at mitigating the consequences of sanctions complications in relations with international organizational structures in the field of megascience.