Al Qaeda and the Taliban knew that NATO and the US would retaliate , so they prepared in advance.
The national hero of most of Afghanistan , Ahmad Shah Massuod , was assassinated on 9 /9/2001 by two foreign al-Qaeda operatives.

http://www.time.com/time/asia/2006/h...b_massoud.html


The murder did serious and long lasting damage to Nato and US efforts in the region.

Massoud's letter to the people of America .
Date: 1998
Afghanistan Online: Masood's Letter To The American People

Massoud had reason to be concerned about the actions some Pakistani officials in 1998.
Over the last two years a new Pakistani administration has been elected . Paki military and law enforcement have been active in the tribal areas, and ( according to The Army Times ) US units have been working with the Pakistani Frontier Corps for over one year.