The terrorist attacks of September 11, 2001, shattered the prevalent optimism in the United States that had blossomed during the tranquil and prosperous 1990s, when democracy seemed triumphant and catastrophic wars were a relic of the past. President George W. Bush responded with a bold and controversial grand strategy for waging a preemptive Global War on Terror, which has ignited passionate debate about the purposes of American power and the nation's proper role in the world.