President Obama's decision to bring 10,000 U.S. soldiers, airmen and Marines home from Afghanistan this year has been both hailed and condemned as a major change in American policy.

Some optimists see it as the beginning of the end of American involvement in the war. Pessimists see it as Americans cutting and running again.

What few people are talking about is what happens to both Afghans and Americans after the last U.S. fighting unit leaves, according to the president's plan, in 2014.

First, Afghanistan won't be a Western-style democracy whether Americans stay or leave. Second, the threat of radical Islamists to Americans and their interests here and around the world won't go away either.

That Afghanistan won't make the progress the most ardent "nation builders" propose should have been obvious. Much of our counterinsurgency doctrine rests upon questionable assumptions that hold that Afghan political institutions will spring up and have the ability to run what is essentially a tribal, warlord-run collection of provinces like a good neighbor. Corruption and kinship networks will give way to an honest, working bureaucracy. That's not likely to happen.

The counterinsurgency doctrine is based on the idea of Clear-Hold-Build. That is, clear the region of enemy soldiers; hold power in the region so that the inhabitants feel -- and are -- safe; and build the political, legal and physical systems needed for a functioning society. So far the "build" phase has received little emphasis. There has been no civilian "surge" to match the military ones.

The assumptions behind this thinking also hold that infrastructure projects will smoothly lead to a better-functioning society. And at the heart of our assumptions is the belief that these political and physical alterations will automatically make the Afghans grateful for our very presence.

On the other hand, the instability and the corruption of the Afghan government make it likely that Taliban-like groups will return when the American protections withdraw to, at best, enclaves over the next few years.

President Obama said the death of Osama bin Laden and the deaths of other al-Qaida leaders over recent months have seriously downgraded the threat. That may be true. But al-Qaida wasn't the only threat. And a return, even a partial return, of some elements of the Taliban to power will be an invitation for anti-Western fighters to reconvene in the mountains of Afghanistan.

More important, the president did not elaborate on the role nuclear bomb-armed Pakistan will play in the future. President Obama mentioned Pakistan only three times in his Wednesday night speech. The neighboring regions of Pakistan are safe havens for the radical Islamists who are likely being supported by the Pakistani intelligence service.

Delaware's Sen. Tom Carper, who has been to the region several times, believes that Pakistan's preoccupation is with the threat from India. In other words, Pakistan could be enticed to clear the border regions if it is convinced India is not behind the Afghan troubles. That's possible, but how would we do it?

Questions like that will continue despite the headlines and wishful thinking that the end of the war is near.

The president will withdraw 10,000 fighting men and women this year and 23,000 more by the summer of 2012, recouping the surge he ordered in 2009. But this move isn't the end. It's the beginning of a new round of questions.