State and government leaders of NATO member countries who gather in Warsaw are to discuss challenges related to deteriorating security environment along NATO’s eastern and southern flanks. Before participating in the first working session, Bulgarian President Rosen Plevneliev said that unity would be demonstrated in Warsaw and that it would be clearly stated that NATO is the main source of security and stability for Bulgaria, for Member States and for Europe as a whole. The Head of State reiterated that in terms of risks to security in the Black Sea region Bulgaria had a clear, unified and coherent position. "We are to express our concerns about the imbalance in the region and the accelerated militarization of Crimea by the Russian Federation. I would say very clearly that NATO must demonstrate commitment to the security of the Member States of the Black Sea region and we expect recognition of the strategic importance of the Black Sea to the security of NATO member states," Rosen Plevneliev added.