Unlike Iraq, Afghanistan was a war we had to fight, and one that served vital national interests: punishing enemies who attacked us on American soil and making sure they couldn't do it again. The original invasion accomplished the first mission and went a long way toward the second. But once Bush turned his attention to Saddam Hussein, he let the Afghan war become an afterthought, lacking sufficient resources and a clear policy.
So what should the policy be? The one identified by Gates and the Joint Chiefs. It makes no difference to our security if Afghanistan is a republic, a monarchy or a theocracy -- as long as it is not a haven for Islamic radicals bent on our annihilation. That's lucky, since there is no reason to think we have the wisdom or the patience to mold the country into anything resembling a prosperous democracy.
Our main power is military, but it has been unable to realize our outsized ambitions. The obvious next step is to try to peel various Taliban factions away from Bin Laden and Co. by offering them a share of power if they give up the fight. Under that approach, we could concentrate our energies on wiping out terrorist camps along the Pakistan border. It also holds the promise of letting us leave in the not-too-distant future without undue risk.
Does it sound like appeasement? Only to those who forget a big key to our recent progress in Iraq -- essentially paying Sunni militias, our onetime enemies, to abandon al-Qaida in Iraq and join with us.
It may be a disappointment to settle for what is merely vital in Afghanistan after the heady days of the early war. But expanding our mission invites disaster, which is worse than disappointment.