That was a great idea. Use a crisis to make positive change. They haven't followed their own advice on Wall Street and the health care issue is still up for grabs, but the idea is sound. Change is hard in normal times, crises make it easier. It's much simpler to build anew when you're knee deep in rubble.

We are knee deep in Afghanistan already. In the next few weeks Obama will decide whether or not we wade in up to our necks. But we've been in that country for eight years and there's no end in sight. The only thing that can save us from more of the same, and worse, is a crisis.

A crisis is brewing in Afghanistan. Actually, crises are always brewing in Afghanistan, but the one coming now is threatening to boil over, melt the kettle and blow up the stove.

That crisis is the Afghani presidential election runoff and the crisis of legitimacy that is sure to follow. Hamid Karzai will win, but it will be a messy, nasty business with messy, nasty consequences. Those events will precipitate a crisis that provides an opportunity, a fleeting opportunity, to get America out of that country. If we're smart enough to take it.

The first thing we need is a reality check. What are our objectives in Afghanistan? What do we want for that torn patchwork quilt forever trying, and failing, to become a healthy nation? What's our goal there, freedom and democracy? Well, people in heaven want orgies. We need to dial down the expectations.

Maybe we just want to build up the Afghan state until it's ready to stand on its own two feet. But Afghanistan doesn't have two feet, it has dozens. If it is to stand at all, it will be on the feet of clans, warlords, druglords, local despots, religious authorities and assorted tribesmen who have precious little in common, save this: they don't respond well to outside force. Nor inside force, for that matter, which is why they're always fighting.

That fight is going to get a lot hotter in the days and months ahead, after the runoff. There will be hurt feelings and wounded pride and a severely diminished belief in the ballot box's power to make things right.

Obama will have a chance to make good use of that crisis. When Afghanistan devolves into chaos, on top of the already occurring civil war, Obama can begin to make the case that it's beyond our power, any power, to heal that nation�not even with 500,000 boots on the ground, much less the 40,000 that General McChrystal wants.

We needn't "cut and run," nor will we. All Obama needs to do is "set down markers." He can give the Afghan government some time to get their act together. He can save face by getting into a holding pattern, keep the already augmented troops in country for a while and "await events." He can even add a few, saying it's a down payment on our commitment to Afghanistan, the rest to be provided when conditions on the ground, in theater, allow. And when those conditions never arise, which they won't, Obama can announce that it's time to "change the mission" and begin to withdraw our troops.

What should our mission in Afghanistan be? To keep our real enemies there from taking over and to keep al Qaeda on the run. We can do that with special-ops and commando raids and Predator strikes on terror camps or anyplace else fanatics are holed up, dreaming of a second 9/11. Just like we're doing in Pakistan.

With our army mostly gone, and hearts and minds, always out of reach anyway, no longer our core mission, our job will be much easier. Our footprint will be smaller, collateral damage can be minimized, and when it inevitably happens, regrettable though it is, it won't hurt our troops engaged in pacification. Because they won't be there. Pacification won't be our mission. Defense will. And the people we'll be defending is us.

Never let a good crisis go to waste. If we don't want to be stuck in Afghanistan for longer than the American people, or the Afghani people, can tolerate, we have to follow that advice right now. The coming crisis will give us a precious chance to get out. It is too good to waste.