Whoever wrote this was reading my mind. What the writer is really saying is that FBI and CIA counterintelligence falsely believed that informants and provacateurs recruited and planted in the cells by these agencies (Freeh's term was "populating" the cells) deceived the agencies. The informants fed misleading and misdirecting information to FBI and CIA, took their money, some of which had to be generous for this kind of work, and then double crossed the agencies.
There is a possibility that the double agents managed to plant or recruit moles in the agencies, and that might not be as hard as it looks with the FBI, because it is hard for them to find people with even Spanish language skills. To find an Arabic speaker would be a real coup for them. So, it is possible that double agent informants managed to plant moles, and the Soviets had moles in there. The Soviets used the Islamic terrorists a lot, and there were reports that the Soviets helped with the OKC bombing.
What we are looking at is going off 10,000 miles to fight a war when the enemy has at least a brigade of soldiers already in the country, and maybe some people in the security agencies helping to hide them. Not a good way to go off to war.
Launching missiles and dropping bombs is fast and easy; identifying and apprehending domestic supporters of these terrorist groups is slow and hard; a body-count is needed to satisy the demand for retribution.
I'm afraid we will have to dramatically increase HUMINT capability. I have no problem with that if it is focussed entirely on collection, but there seems to be a strong tendency to morph human collection exercises and assets into operations.