“Before 9/11, there was an individual by the name of Khalid al- Mihdhar who came to be one of the principle hijackers,” Mueller began. “He was being tracked by the intelligence agencies in the Far East. They lost track of him.”

“At the same time, the intelligence agencies had identified an Al Qaeda safe house in Yemen,” he continued. “They understood that that Al Qaeda safe house had a telephone number, but they could not know who was calling into that particular – that particular safe house.”