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 development, help allies and kill enemies.

It’s true that the security situation in Afghanistan has deteriorated considerably. While it is nothing like Iraq in 2006 — civilian deaths are a tenth as numerous — parts of the country are effectively controlled by the Taliban. Other parts are no man’s land. But these areas are sparsely populated tracts of countryside. All the major population centers remain in the hands of the Kabul government. Is it worth the effort to gain control of all 35,000 Afghan villages scattered throughout the country? That goal has eluded most Afghan governments for the past 200 years and is a very high bar to set for the U.S. mission there.