The Post-Cold War world was considered to be the end of the tensions and the great time of global trade. Soviet agreed to dissolved the Warsaw Pact and gave the independence to the states where it once occupied. Fukuyama wrote in his book that “the end of cold war is the end of history”. China was then permitted to join the World Trade Organization. There are two choices of US foreign policy to lead the new world: To Dissolve the military allies for mutual trust or to use its global agenda.

US decided to follow its global agenda to prevail its systems and hegemony. Russia and China was surrounded in which the competitions have arisen. After 11/9/2001, US invaded several states in Middle East and enlarged the NATO members. According to US General Wesley Clark, US planned to invade seven countries in the Middle East within 5 years.
Through its global hegemonic policy and the spread of democracy, US toppled the countries and states that opposed to subjugate to its powers.The rise of extremism and terrorism made the situation worse. The Distrustful relations between the NATO and Russia as well as China rose up. Russia invaded Georgia in 2008, annexed the Crimea in 2014 to prevent the Western Expansion, and rushed to intervene the Syrian war in 2015 to push back and expanded its influence. For Russia who feel insecurity from all directions have struggled to spread its buffer zones, in which the West considers its as the attempting to rebuild the Russian Empire.
The Black Sea should be considered to be the buffer zone between the NATO and Russia. Any attempt to dominate the region will be considered by both sides as the serious threat.