Answer: Concert of Europe, in the post-Napoleonic era, the vague consensus among the European monarchies favouring preservation of the territorial and political status quo. The term assumed the responsibility and right of the great powers to intervene and impose their collective will on states threatened by internal rebellion.
Explanation:
“Society was liberalized, and Gorbachev sought détente with the USA so as to be able to transfer funding from defense to civil society. He declared that he would not support Communist regimes in other countries if their peoples were opposed to them. He thus started a chain reaction which led to the fall of communism in Europe.”
Byzantine Empire and the Turks. I hope this helps!