The trial of three Birmingham men convicted Thursday of plotting to launch a "catastrophic" suicide bombing attack in the United Kingdom revealed that al Qaeda has developed a new strategy to target the West.
The new strategy involves a teacher-training approach in which a select few Western operatives are taught bombmaking and other aspects of terrorist tradecraft in the tribal areas of Pakistan and are then instructed to return back to the West to "spread the knowledge" to a larger body of Islamist extremists keen on launching attacks.
The new approach is a response to the growing toll of drone strikes which have made travel to the tribal areas increasingly perilous for Western recruits and significantly diminished al Qaeda's ability to orchestrate terrorist plots from the region.
The trial revealed that terrorist groups in Pakistan are actively dissuading Western militants from making the trip.
Two of those convicted Thursday -- Irfan Naseer and Irfan Khalid -- received 40 days of terrorist training in the tribal areas of Pakistan in the spring of 2011, mostly inside houses in the valleys of Waziristan.
In conversations bugged by British police, the plotters described being handled by al Qaeda operatives and having attended a training camp run by Harakat al Mujahideen, a Pakistani terrorist group closely affiliated with al Qaeda.
The recordings revealed that like other Western militants before them, they were provided detailed instruction in the tricky and potentially hazardous methods to make bombs out of substances readily available in the West, and practiced detonating them. Their instructors included Arabs and Pakistanis.
They also were taught how to put poisons in face creams.
And their teachers emphasized they should put nails inside their bombs, to act as razor-sharp shrapnel.
Naseer, a pharmacy major and the plot's alleged ringleader, was heard recalling how one of their trainers had said the July 7, 2005, London bombers had missed an opportunity to kill more people by failing to put nails in their devices.
Naseer commented on how they were given so much information that they had accumulated 30-40 pages of notes.
They were told the smaller the cell they recruited the better, illustrating al Qaeda's move away from spectacular attacks on the 9/11 scale toward smaller strikes that have a better chance of getting through.
In the recordings played in court, Naseer said his cell should keep the numbers launching the attack in the United Kingdom to around half a dozen. The recordings, however, indicated the cell's plans grew increasingly ambitious with talk of launching an attack bigger than the 2005 London bombings.
The need for less ambitious attacks was previously stressed by two senior American al Qaeda operatives: al-Qaeda in the Arabian Peninsula cleric Anwar al-Awlaki and Adnan Shukrijumah, an operative believed to be still at large in Pakistan.
An internal al Qaeda strategy document, authored in around 2009, and recovered in 2011 from a Berlin operative, had called for a greater emphasis on low-cost low-tech attacks by Western militants, whom it said should be quickly trained in the tribal areas of Pakistan.
Teaching Westerners to teach back home
In Pakistan, Naseer and Khalid's al Qaeda handlers had a new "command" for them: go back and teach others.
Naseer revealed this to an associate, keen on traveling to Pakistan, who he and Khalid wanted to stay in the United Kingdom to participate in the plot.
"AQ's main aim is... the knowledge that they give us, [they] want more and more people [to] have [the knowledge] in Europe. So they can start whacking [attacking] there, yeah, do you understand?," Naseer is heard telling the associate in the recordings.
Analysts say that if al Qaeda manages to put into practice their new teacher training model, it will raise alarm bells with Western security services because it would reduce the need for Western militants to travel overseas for terrorist training.
"This seems to be a product of al Qaeda's desperation to try to get an attack through, but it's a potentially scary development," Raffaello Pantucci, a senior fellow at the Royal United Services Institute, who closely followed the trial, told CNN.
While Islamists militants have access to many bombmaking recipes online, analysts say they often contain potentially fatal errors and have been seen by militants as a poor substitute to hands-on training by an instructor schooled in the art of bombmaking.
Security services fear the presence of such instructors on Western soil could be a game changer.
Message from al Qaeda: Stay Put
The Birmingham case revealed that al Qaeda had begun actively dissuading recruits from going to Pakistan.