The 2001 attacks, in which terrorists hijacked airliners to use as guided missiles, sparked a major overhaul of the U.S. intelligence community.
Yet on Christmas Day, a would-be suicide bomber, Umar Farouk Abdulmutallab, 23, nearly blew up an airliner in flight from Amsterdam to Detroit. President Obama said Abdulmutallab was acting on orders from al-Qaida's branch in Yemen. Not only did he manage to get explosives on the aircraft, but he got on the U.S.-bound flight even after his own father had warned the U.S. Embassy in Nigeria of his son's growing radical Islamist sympathies.
Professor Amy Zegart, who teaches on intelligence issues at UCLA, says the Christmas Day attack was clearly a major intelligence failure.
"I think it's hard to conclude that it's an intelligence success when somebody who is a foreign national, and there's a tip by NSA [National Security Agency] six months before - or however many months before, from August - whose father actually warns American officials that he's become an extremist, gets on an airplane and tries to blow it up, and the pieces were in the system and nobody thought to raise the alarm," she said. "How can you conclude that it's anything but a failure?"
In the post 9/11 intelligence reorganization, a new Office of National Intelligence was created to oversee the 16 disparate agencies dealing in intelligence. The Department of Homeland Security was born to pull together domestic intelligence efforts, including airport security. And, perhaps most significantly, the National Counterterrorism Center (NCTC), was set up so all the intelligence agencies could pool information related to terrorism.
Current and former intelligence officials argue that the information on Abdulmutallab was in fact shared. But, as former CIA director General Michael Hayden tells VOA, it was never properly analyzed - connecting the dots, as intelligence officers like to call it - to raise warning signals.
"These dots look very powerful and connected in retrospect," he said. "But given the vast ocean of dots that analysts have to work with prospect, this is very daunting task every day, and for the most part they get it right. Here they didn't. They didn't connect the dots, or at least didn't connect them in time to take action."
Amy Zegart says the system works better than it used to, particularly with regard to the National Counterterrorism Center. But, she adds, the intelligence bureaucracy has become more cumbersome than ever.
"By most accounts NCTC has been a dramatic improvement over the fragmented system we had before," she said. "But we seem to be so bureaucratized with all these reforms, with so many watchlists and so many fusion centers and so many procedures that the system can't work. The bureaucracy is strangling itself.
But General Hayden says errors will occur because intelligence agencies are not infallible, especially when confronted with a tsunami of information from a wide range of human and electronic sources.
"The real challenge here is the analysis that puts the information together. These young folks get it right most all the time, but it is unreasonable to expect they will get it right all the time in every instance," he noted.
Zegart warns against another rush to overhaul of the intelligence system in the wake of the Christmas Day incident.
"I hope what we will not see is yet more reorganization because as you know, whenever there's an intelligence failure, our immediate reaction is, let's create another agency, or let's reorganize the ones we have," he added. "That's not what we need to be doing here. We need to make the system we have work better, not create a new system."
Former CIA director Hayden agrees.
"What you have is a very difficult task that seems to have worked quite well over the past eight years," he explained. "In this instance it didn't. But given the reality that you can never be 100 percent successful, when you have a failure, the initial instinct to go back and condemn the entire structure and the entire system is actually counterproductive and, frankly, quite destructive.
Nevertheless, what Amy Zegart calls the finger-pointing of blame has already begun, with the State Department and the National Counterterrorism Center as particular targets. At least two congressional committees have already planned investigative hearings on the Christmas Day plot.