Existing security regimes have been highly instrumental in restraining provocative behaviour by state actors. Yet, they have obviously lagged behind today’s security environment. Growing military and political tensions point to the necessity to close multiple gaps and adapt security regimes to the needs of the present day. This, in turn, leads to the discussion about the relevance and effectiveness of regional and subregional international organisations in the realm of security. The session will explore Eastern Europe-specific gaps in security regimes and which institutional lacunae can be addressed as a matter of priority.