AP Photo

At almost nine years, the U.S. war in Afghanistan is the longest in our history, surpassing even the Vietnam War, and it will shortly surpass the Soviet Union’s own extended military campaign there. With the surge, it will cost the U.S. taxpayers nearly $100 billion per year, a sum roughly seven times larger than Afghanistan’s annual gross national product (GNP) of $14 billion and greater than the total annual cost of the new U.S. health insurance program.1 Thousands of American and allied personnel have been killed or gravely wounded.

The U.S. interests at stake in Afghanistan do not warrant this level of sacrifice. President Obama justified expanding our commitment by saying the goal was eradicating Al Qaeda. Yet Al Qaeda is no longer a significant...