British Home Secretary Alan Johnson said today he did not believe Abdulmutallab had been acting alone, and that police and security services in Britain were examining whether he was radicalized while studying at University College London between 2005 and 2008.
The incident was a signal that the U.S. government needs to review the process by which individuals such as Abdulmutallab, are placed on security lists, Napolitano said.
"One of the things that we are doing is going backward. What were the facts that led up to this event, how did this individual get on the plane, why wasn't he flagged at a higher screening level, how did he get an explosive substance onto the plane," Napolitano said on "GMA" today.
In May 2009, a report by the Justice Department Inspector General found problems with how the FBI was managing the terrorism watch list, noting, "We found that the FBI failed to nominate many subjects in the terrorism investigations that we sampled, did not nominate many others in a timely fashion and did not update or remove watch list records as required. Specifically, in 32 of the 216 (15 percent) terrorism investigations we reviewed, 35 subjects of these investigations were not nominated to the consolidated terrorist watch list, contrary to FBI policy."
Napolitano's remarks on Sunday to CNN brought a sharp rebuke from Rep. Peter King of New York, the top Republican on the Homeland Security Committee.
"It's not reassuring when the secretary of Homeland Security says the system worked," King said. "It failed in every respect."
The Senate Security and Governmental Affairs Committee will hold a hearing next month to examine U.S. security measures.
"We were very lucky this time, but we may not be so lucky next time, which is why our defenses must be strengthened," committee chairman Sen. Joe Lieberman, I-Conn., said in a written statement. "What we know about the Abdulmutallab case raises two big, urgent questions that we are holding this hearing to answer: Why aren't airline passengers flying into the U.S. checked against the broadest terrorist database and why isn't whole body scanning technology that can detect explosives in wider use?"
Abdulmutallab's family had warned U.S. authorities of the increased radicalization of their son, a student at a London university until 2008. His father went to the U.S. Embassy in the capital city of Abuja Nov. 19 to report that he believed his son was being radicalized in Yemen, according to a senior State Department official.
On Nov. 20, the embassy sent out a cable to U.S. embassies worldwide and to the U.S. counterterrorism community alerting them to the information that was provided by Abdulmutallab's father. An intelligence source told ABC News the cable from the State Department noted that the father expressed concern about his son's association with extremists.
There are hundreds of walk-ins to embassies reporting various threats. The State Department's cable triggered the entry into a database run and maintained by the National Counterterrorism Center, but no further threat information was entered because the State Department cable did not contain any specific information about who the son was associated with and the threat they posed.