Not everyone thinks it a good idea to send more troops to Afghanistan. Sen. James Webb, a Vietnam combat veteran and one of those who were considered for the vice-presidential slot on the Obama ticket, is highly skeptical. He sees Afghanistan as a potential sponge soaking up ever growing numbers of American soldiers – Vietnam revisited.

The news from Afghanistan is not good at the moment. Violence is up about 30 percent over last year and the Taliban are better armed and tactically more sophisticated. Last week Adm. Mike Mullen, chairman of the joint chiefs of staff, said trends in the country were bad and only likely to get worse next year.

The British ambassador to Kabul told a French diplomat recently, "the current situation is bad, the security situation is getting worse, so is corruption, and the government has lost all trust."

Anxious not to be seen as leaving a total mess for their successors, the George W. Bush administration has launched a number of reviews of Afghan policy. Part of the process is simply the higher policy circles finally confronting long-established but painful facts on the ground.

For example, the government in Kabul is incapable of tackling the Taliban. It is corrupt and Afghanistan has always had a weak central government whose writ does not run in the provinces. Wishing it different does not make it so.

In fact, one proposal, to boost the Afghan national army to 130,000 so that Afghanistan could take control of its own security, would cost more than the entire national budget. It would create a long-term dependency on foreign, mostly U.S. aid.

The alternative is more foreign troops. Bush has committed to send an additional 8,000 early next year but the local commander, Gen. David McKiernan, is already calling for 15,000 more on top of that. And one of the defense reviews being undertaken calls for a five- to 10-year military plan for pacifying the country. It's not clear that a President Obama would embrace that sort of commitment.

Afghanistan offers no simple solutions. U.S. Defense Secretary Robert Gates wants to hit the opium trade that provides the Taliban with $60-80 million a year, but several NATO allies demur saying it is outside the scope of their mission.

Then there is Pakistan whose tribal areas offer a safe haven to Taliban fighters and whose government, public, and intelligence services have three different views on how to handle the matter, none of which coincide completely with the U.S. view.

The reviews being undertaken need to clarify what the United States wants to achieve in Afghanistan. Is it to deny bases to al-Qaida from which it could plan attacks against the United States? Or is it to defeat the Taliban, stand the central government on its feet, and develop the economy? Or is it something in between?

The goal should be made clear before any more American troops are thrown into an open-ended commitment. And if the current reviews don't spell it out, clarifying that goal should be the new president's top priority.