The article presents the Baltic-Black Sea region in the military-political dimension, as well as explores the potential benefits of this cooperation for European security. The study offers some important insights into the historical preconditions for the formation of the Union according to the Baltic-Black Sea Arc. This paper attempts to show the importance of international political and security potential of Ukraine and its influence on the formation of the Baltic-Black Sea Union. The Baltic-Black Sea Union is seen as an effective counterweight to Russia’s expansion into the West, whereby Ukraine could serve as a guarantor of European stability. The article analyzes opinions of international experts on the implementation of the Baltic-Black Sea Union, as well as compares the military power of potential members of the union with the military forces of advanced countries. This study provides an important opportunity to advance the understanding of the benefits for Union members and European countries and how the United States can help implement the idea of project. The analysis emphasizes the functions of the Baltic-Black Sea Union, potential NATO assistance and how the Union will ensure the stability of its forces in Europe. It is summarized why the countries of the Baltic-Black Sea arc can act as a guarantor of protection against Russian aggression.