"Few at the time or since have questioned the costs or the risks associated with Berlin in 1948–1949. From that time until the end of the Cold War, the Allies’ presence in West Berlin remained the embodiment of Soviet frustration and, despite the city’s real vulnerability, of America’s commitment to halt aggression. Berlin became an important intelligence site for both sides—an opportunity to dig listening tunnels, recruit spies and counteragents, and monitor the other’s activities—but for the West it also provided an invaluable means to observe the communists’ military personnel, formations, and equipment. Moreover, less than four years after World War II, two million West Berliners—and, by extension, the entire population of western Germany—were suddenly transformed into America’s democratic protégés. Truman’s actions in 1948–1949 replaced appeasement with firmness and selective engagement with an expansive definition of US interests and prestige. The Berlin airlift also redefined America’s view of its Cold War partnerships to include populations unwilling or incapable of defending themselves from aggression, who would be rescued by decisive US action. In real as well as symbolic terms, the “Berlin syndrome” wiped out the Munich nightmare that had haunted the West for a decade."