Where did you get that idea?
With a few notable exceptions, they were able to live among us for some time, then pull off a complex operation that resulted in the deaths of perhaps three thousand of our fellow citizens.
They can be good, when they want to be. Most of the people who went through their camps were designed to be a Praetorian Guard corps for the Taleban government. A few were trained for covert operations and terrorism, however.
Be Seeing You,
Chris