This year marks the 30th anniversary of Germany's reunification at the end of the Cold War.
More than a generation later, the diplomacy that made it possible is still a fount of controversy. There is a raging debate — involving scholars, former policymakers and even a former secretary of state — over whether U.S. and West German officials promised their Soviet counterparts that NATO would not expand into Eastern Europe.
That debate can seem incredibly narrow: It fixates on who said what to whom on some particular occasion. Yet the reason the argument continues is that it is a stalking horse for a much bigger dispute over whether America should pull back from the world.