What are we doing in Afghanistan?

The Washington Post ran a story on Saturday declaring that, "The lull in the hunt for al Qaeda and Taliban leaders in Afghanistan has Afghans and Americans alike demanding that the U.S. military make clear what it is doing here and how much longer it plans to keep doing it."

Yeah, it sure as hell would be nice to know what we are doing over there. And, golly, it also might be nice to know a) how the war in Afganistan has lessened the threat of terrorism, b) what good the war has brought, outside of setting a dangerous precedent where a Western power swoops in to purge a political entity (the Taliban) with the applause of nearly everyone in the international community, and c) how any of this action will make Americans safer, in the long run. 'Cause frankly, I haven't seen a substantial argument address any of those three points and would welcome one which didn't have to resort to rhetoric like "It's too early to be critical; we're in this for the long haul" or "What did you expect us to do? Nothing!?".