Eight years ago, a small number of U.S. personnel, working in tandem with local Afghan leaders, entered Afghanistan with a defined aim: to punish al-Qaida and overthrow the Taliban regime that harbored them. Over the past year, that mission has morphed into the much broader objective of rebuilding the Afghan state and protecting Afghan villages. Most recently, America's top commander in Afghanistan, Gen. Stanley McChrystal, said a new strategy must be forged to "earn the support of the [Afghan] people . . . regardless of how many militants are killed or captured."
Such an undertaking, amounting to a large-scale social-engineering project, is unwarranted. The cost in blood and treasure that we would have to incur -- coming on top of what we have already paid -- far outweighs any possible benefits, even accepting the most optimistic estimates for the likelihood of success.
The essential question now is not whether the war is winnable, but whether the mission is vital to U.S. national security interests.