The map of Europe at the end of WWI had never intended to be permanent, but the new Cold War between the Soviet Union and America (and by extension the democratic and capitalistic West) had led to the divisions in Europe and Asia being an established part of the geopolitical landscape.

Detente was a doctrine in the 1970s which accepted those divisions and map as permanent. This gave the Soviet government legitimacy, as well as the territory and political hold they had on Europe legitimacy as well. Detente was more important to the Soviets than it was America, however, from the US point of view it followed a doctrine of realpolitik.

John Lewis Gaddis points to several world leaders who were not prepared to deal in Dentente which entrenched the cold war conflict as the status quo; they were Ronald Reagan, Margaret Thatcher, Pope John Paul II, Lech Walesa and Mikhail Gorbachev. (more)

When Czechoslovakia threatened to transition to democratic capitalism Leonid Brezhnev implemented what came to be known as the Brezhnev Doctrine; the USSR could violate the sovereignty of any country in which an effort was being made to replace Marxism-Leninism with capitalism. Beware the morally unassailable courtesy of ideology when they have the resources of a nation-state behind them. (more)