OPINION: Petraeus' problem: 'victory' or exit

Eugene Robinson is a nationally syndicated columnist for The Washington Post.

The good news? Nobody has to pretend anymore that Gen. Stanley McChrystal knew how to fix Afghanistan in a year. The bad news? We're supposed to pretend that Gen. David Petraeus does.

President Obama was right to sack McChrystal, whose inner circle, according to Rolling Stone magazine, was as serious as a frat-house keg party. And it was a brilliant move to turn to Petraeus, who is made of purest Teflon. Critics who might have been tempted to blast Obama for this change can hardly object when he has given the reins to the man who averted a humiliating U.S. defeat in Iraq.

Note, however, that I didn't credit Petraeus with "winning" in Iraq. He didn't. What he managed to do was redeem the situation so that the United States could begin bringing home troops. If Obama's aims in Afghanistan are recalibrated to accommodate objective reality, then Petraeus can succeed there, too. But this means that the general's assignment should be narrow: Lay groundwork for a U.S. withdrawal to begin next summer, as Obama pledged.

After relieving McChrystal of his command Wednesday, Obama called in his national security team and read the riot act, ordering officials to play nice.

But all the comity in the world won't resolve the tension between those who believe our goal in Afghanistan should be defined as "victory," and those who believe it should be defined as "finding the exit." History is on the side of the "exit" camp, and the fact is that at some point we're going to leave. The question is how much time will pass - and how many more young Americans will be killed or wounded - before that day comes.

Petraeus is far too good a politician to fall into the trap McChrystal did. He won't allow any daylight between himself and the civilian leadership.

But ultimately, there's going to be no way to avoid the central question: What kind of Afghanistan will we leave behind?

One answer would be that we have to leave in place a durable, functional central government that has full legitimacy and control within the nation's borders. This would provide us with an ally in a dangerous region and ensure that Afghanistan would never again be used as a launchpad for al-Qaida's attacks.

But to get the country to that point, given where it is now, could take a decade or more of concentrated attention. It would mean not just defeating the Taliban but molding Afghan president Hamid Karzai's regime into an honest, effective government. This would be a tall order even if Karzai were a stable, consistent and loyal partner. Does anybody believe that's what he is?

A better answer would be to leave behind an Afghanistan that no longer threatens the United States or its vital interests. Nation-building would be the Afghans' problem, not ours.

Petraeus succeeded in Iraq because he realized he couldn't create an Athenian democracy in Baghdad. But the highly imperfect Iraqi government is light-years beyond what the general can likely achieve in Kabul. Even after the war, Iraq was left with modern infrastructure, a sophisticated population and a sizable percentage of the world's oil reserves. Afghanistan has none of these advantages. The political culture is medieval; the populace is poor, uneducated and wary of foreign influences. Afghanistan apparently has great mineral wealth, but no mining industry to dig it out or railroads to get it to the marketplace.

Testifying before Congress, Petraeus was less than definitive when asked about Obama's July 2011 deadline. Because he has such credibility in Washington, his view will be more important than McChrystal's ever was. But I hope that by putting Petraeus in charge, Obama hasn't consigned us to a longer stay.