At the heart of Gen. Stanley McChrystal's request for a major surge in troops is the assumption that we are failing in Afghanistan. But are we really? The United States has had one central objective: to deny al-Qaeda the means to reconstitute, to train and to plan major terrorist attacks. This mission has been largely successful for the past eight years. Al-Qaeda is dispersed, on the run and unable to direct attacks of the kind it planned and executed routinely in the 1990s. Fourteen of the top 20 leaders of the group have been killed by drone attacks. Its funding sources are drying up, and its political appeal is at an all-time low. All this is not an accident but rather a product of the U.S. presence in the region and efforts to disrupt terrorists, track funds, gain intelligence, aid...