“It’s not like 9/11,” Brennan said, adding that the “system didn’t work as it should have” due to “lapses” and “human error.”

“There wasn’t an effort to try to conceal information,” he said in reference to the well-chronicled competition and turf wars between security agencies prior to the 2001 attacks that was later blamed for the failure to prevent them.

“There is no smoking gun piece of intelligence out there,” Brennan said of the failed Christmas bombing, allegedly by a Nigerian man who boarded the flight from Amsterdam, Netherlands, to Detroit, Michigan with explosives in his underwear.

The suspect’s father, a leading banker in Nigeria, warned U.S. authorities before the attack that his son might be involved with Islamic extremists.

Brennan said the father’s information was part of “bits and pieces” of information that were never connected by intelligence officials to properly target the suspect.

“That was certainly an alert that came to our attention,” Brennan said of the father’s warnings. “He said, ‘He’s consorting with extremists in Yemen.’”

However, Brennan rejected another potential warning sign – that the suspect purchased the airline ticket with cash in Ghana before traveling to Nigeria for the first leg of his journey.

“A lot of people buy their tickets in Africa with cash,” Brennan said. “People in Amsterdam airport didn’t know he bought ticket for cash.”