November 9th marks the 20th anniversary of the fall of the Berlin Wall.

Most analysts and historians agree that former Soviet leader Mikhail Gorbachev played a pivotal role in the events leading up to the fall of the Berlin Wall and beyond. His policies of "perestroika" - restructuring - and "glasnost," or openness, paved the way for the dissolution of communist power in Eastern Europe and ultimately led to the collapse of the Soviet Union.

Robert Legvold from Columbia University says a key factor was Gorbachev's decision that he would not use force to suppress reformist aspirations in Eastern Europe.

"Increasingly he made it apparent to the East Europeans that the Soviet Union would not do what it had done many times in the past: 1953 in Berlin, 1956 in Hungary and Poland, 1968 in the Czech Republic and so on," Legvold said.

In July 1989, the so-called "Brezhnev Doctrine" was replaced by what one Gorbachev adviser described as the "Sinatra Doctrine," based on the singer's song "My Way". In other words, the adviser said East European countries were now able to go their own way - politically and economically.