On the evening of November 9, 1989, an East German party spokesman, fumbling answers at a routine press conference, mistakenly announced that travel restrictions to West Berlin had been lifted immediately. Berliners on both sides of the Wall heard him on television, walked to the checkpoints, and demanded to be let through. Border guards, with no orders and no idea what to do, eventually opened the gates. By morning, citizens were standing on top of the Wall with hammers, taking it down piece by piece.
The fall of the Wall was the visible moment of a process that had been gathering speed for years and would accelerate after. Within a year, every Communist regime in eastern Europe had fallen — most peacefully, only Romania bloodily. Within two years the Soviet Union itself dissolved, by signature, without a war. Germany was reunified within eleven months. The Warsaw Pact was disbanded. NATO did not, as Gorbachev had been led to expect, refrain from expanding eastward; it did the opposite. The United States, briefly, was the only superpower left standing, and announced — with characteristic confidence — that liberal democracy was the end of history. None of this had been forecast by the Western intelligence services that spent the Cold War watching for it.
We are living through the unwinding of the post-1989 settlement. Russia's invasion of Ukraine, China's challenge to American primacy, the rise of illiberal democracies in Hungary and elsewhere — each is, in its way, a renegotiation of terms that were set on the night of November 9, 1989. The 'unipolar moment' lasted about thirty years.