Today we find out that it was a CIA outpost with local Afghans and that the bomber was invited in:
The Associated Press has learned that the suicide bomber who killed seven CIA employees at a remote outpost in southeastern Afghanistan had been invited onto the base and was not searched.
Now McChrystal's decision to pull our troops back from border positions to focus on population protection may make a little more sense. Interdicting the border to keep bad guys out and to keep them from freely moving across the border to rest and re-equip always seemed important to me.
It may be that instead of US troops on the border, we're counting on the CIA (and perhaps special forces) to organize locals to provide manpower and--more importantly--information on Taliban movements to these para-military outfits so they can call in the smart bombs on the bad guys.