It has been painful for American military forces to be involved - and taking casualties - in faraway Afghanistan without a clear idea of what a satisfactory outcome there would be.

The United States is beginning a withdrawal of U.S. forces from Afghanistan - slowly - and with no assurance that the al-Qaida terrorists who plotted the 9/11 attacks won't be able to regain a foothold in that country.

There currently are about 100,000 American troops in Afghanistan. It is now reported that 800 U.S. National Guard troops will be withdrawn and returned home this month.

President Barack Obama has ordered the withdrawal of 10,000 more American soldiers by the end of this year, and a further reduction of 23,000 American soldiers from Afghanistan by September 2012 is planned.

That's a long time off, though, and even if the partial withdrawal is achieved, it would leave more than 65,000 Americans mired in the Afghanistan War. Plus, Obama's planned drawdown is taking place faster than what U.S. military commanders in Afghanistan thought wise.

So what, exactly, is the U.S. military strategy, and what positive result do we hope to attain, besides just keeping our opponents from taking power?

We are seeking to empower our Afghan military allies. Obviously, we don't want to turn the country over to the forces we long have been fighting. But most Americans have little idea of our specific military objectives. While military outcomes cannot be surely predicted, what, in general terms, are American soldiers expected to achieve, and by when?

The president has a difficult task in deciding what to do in Afghanistan, and we should not have unreasonable expectations of what may happen in that peculiar, distant war. But without at least some notion of what the military or political results should be, it is hard for most Americans to understand our prospects for success.

No one wants American military forces to remain in Afghanistan forever.

But neither do we want to leave too soon, and open the door to al-Qaida before legitimate Afghan forces can establish a degree of security.