By Paul Cruickshank, CNN Terrorism Analyst
The trial of "underwear bomber" Umar Farouk AbdulMutallab was cut dramatically short Wednesday when the Nigerian pleaded guilty to all the counts against him.
While the prosecution's opening statement contained significant new detail about the Christmas Day 2009 plot to blow up an airliner approaching Detroit - mainly from AbdulMutallab's initial 45-50 minute, tell-all interview with FBI agents at the hospital where he was treated after the attack - the short duration of the trial also left many questions unanswered, most notably the role played in the plot by Anwar al-Awlaki, the American-Yemeni militant cleric killed in a drone strike last month.
After his death, senior Obama administration officials emphasized al-Awlaki's operational role within al Qaeda in the Arabian Peninsula (AQAP), al Qaeda's affiliate in Yemen, labeling him the head of the group's external operations and stating he played a lead role in planning and directing the "underwear bomber" plot.
U.S officials had already warned about his growing role in terrorist planning earlier in the year. "Let me underscore, Awlaki is no mere messenger but someone integrally involved in lethal terrorist activities," State Department counterterrorism coordinator Dan Benjamin warned in April.
At trial, it was revealed that AbdulMutallab only connected with al Qaeda operatives in and around August 2009 after he traveled to Yemen from the United Arab Emirates. In his initial interview with the FBI, he stated that the reason for going to Yemen was to become involved in violent jihad against the United States.
Little was revealed in court about how the son of a Nigerian multimillionaire, educated at elite schools and a top London University, was radicalized. After pleading guilty Wednesday, AbdulMutallab stated, "I was greatly inspired to participate in jihad by the lectures of the great and rightly guided mujahideen who is alive, Sheikh Anwar al-Awlaki."
While trying to make contact with AQAP, he told the FBI he was introduced in a mosque to an operative named Abu Tarak, who became his principal handler.
According to AbdulMutallab, the two frequently discussed ways to attack the United States. In late November Abu Tarak enlisted AbdulMutallab in AQAP's plan to attack an American airliner. The speed of his recruitment illustrated AQAP's opportunism. As noted by the prosecution, AbdulMutallab was the perfect recruit - a westernized English speaker with a visa to the United States. The plot progressed with astonishing speed after he agreed to participate.
Hands-on master bomb maker
After agreeing to the operation, AbdulMuttallab told the FBI he met with the Saudi bomb maker responsible for building the underwear device, who instructed him how to detonate it. Although the name of the bomb maker was not named in court, U.S. authorities believe he is Ibrahim al-Asiri, a 29-year-old Saudi, who has developed a genius for bomb design but remains a shadowy figure. Before moving to Yemen four years ago, al-Asiri was part of an al Qaeda-affiliated cell in Saudi Arabia targeting oil facilities, according to U.S. authorities.
As well as constructing the underwear device, U.S. authorities believe al Asiri built the "printer-bomb" devices al Qaeda attempted to explode aboard cargo jets over the Eastern Seaboard of the United States in October 2010. Both devices contained a main charge of PETN, a white powdery explosive which conventional "single beam" X-Ray machines are rarely able to detect. In 2009, al-Asiri fitted out his own brother - Abdullah al-Asiri - with a PETN-based underwear bomb to kill Prince Mohammed bin Nayef, a top Saudi security official. The device killed his brother instantly, but failed to kill its target. U.S. and Yemeni officials believe al-Asiri is still at large in Yemen. There is arguably no al Qaeda figure anywhere in the world who currently poses more of a threat to the United States.
At trial, it was revealed the bomb maker's fingerprints were found on tape used to hold together the underwear device. "When the FBI took that tape off, they found fingerprints on the inside, on the sticky part in a place where only the person who made the bomb could have done it," the prosecution stated.
Three weeks wearing explosive underwear
The Nigerian also received training in how to detonate the device from his handler Abu Tarak, who told him that the device would make the plane crash, killing everybody on board. AbdulMutallab was delivered the device by Abu Tarak on December 6 or 7, 2009, with instructions that he target a U.S. passenger jet over U.S. soil. After recording a martyrdom video, AbdulMutallab flew from Yemen to Djibouti, then to Ethiopia and Ghana and then on to Nigeria before booking a ticket to the United States from Amsterdam. The final leg was Northwest Flight 253 to Detroit. According to the prosecution, the roundabout journey was designed to cover the defendant's tracks because of AQAP's increasing presence in Yemen. The only reason he made a brief transit through Nigeria was because Ghana at the time prevented non-citizens from taking such intercontinental flights. AbdulMutallab revealed to the FBI in his initial interview that he wore the underwear device on every leg of his almost three-week journey, and he forbade maids from cleaning his hotel rooms out of fear his device would be discovered.
Most of the bomb worked
The trial revealed new details about the design of the device, which was made with no metal parts in order to evade airport metal detectors. A specially sewn pouch in his underwear contained the main PETN explosive charge which was connected to a TATP detonator - the same primary explosive Najibullah Zazi planned to use in a plot to blow up subway cars in New York in September 2009 and shoe bomber Richard Reid attempted to detonate on a transatlantic flight heading to Los Angeles in December 2001, according to authorities. The main explosive charge in Reid's device also was PETN.
The initiation for the device was a syringe connected to his underwear filled with two easily obtainable chemicals - potassium permanganate and ethylene glycol (a chemical found in antifreeze) which catch fire when mixed. As the plane made its final approach to Detroit, AbdulMutallab returned from the washroom in which he had prepared himself for death, put a blanket over himself, lowered his underwear, and plunged the syringe, mixing the two chemicals and setting them afire. The loud pop passengers heard was likely the flame melting and bursting the syringe, a Western explosives expert told CNN. According to the prosecution, this flame in turn successfully detonated the TATP, but the PETN main charge was not detonated. Instead, some of the PETN started burning, creating a fireball on AbdulMutallab's lap. "While that fireball was on him, the defendant sat there. He didn't move. He was expressionless. He was completely blank," the prosecution stated.
Those on-board the plane may have been very lucky. PETN can be easily detonated by relatively small amounts of primary explosives such as TATP, according to the Western explosive expert, made aware of details on the bomb design revealed Tuesday in court. The expert told CNN that one of the likeliest explanations for the failure of the underwear device to fully detonate was the wear and tear on the device during AbdulMutallab's transit through Africa. "The fact he was wearing it so long could have interfered with its proper functioning, either by desensitizing the main charge or disrupting the mechanics of the bomb," the expert told CNN.
Device more powerful than first reported
Counterterrorism sources initially stated that the assumption was the underwear device may have contained around 80 grams of PETN. At trial it was revealed that about 76 grams of PETN did not burn and was recovered by authorities from the floor of the plane near his seat. And the prosecution revealed that FBI bomb experts were later able to extrapolate from the size of the pouch in AbdulMutallab's underwear that the device carried 200 grams of PETN.
The prosecution, while making clear that the device would likely have endangered the safety of the aircraft, did not state whether this quantity would have been enough to bring down an aircraft if detonated at a window seat above the wing - the position of AbdulMutallab's 19A seat on the Airbus A330. British authorities have stated that the 400 grams of PETN hidden inside a printer cartridge in the air cargo bombing attempt last October had the potential to bring down a plane.
Ability to communicate with handlers
The trial revealed that the FBI found a slip of paper in AbdulMutallab's shoes on which was written an encryption code. According to the prosecution, this was a password for encryption software used by al Qaeda given to him so that he could communicate online with his handlers before boarding Flight 253. Such encrypted communications have in particular been associated with al-Awlaki. His group's increasing ingenuity in masking its communications was revealed in the UK trial of Rajib Karim, a British-Bangladeshi operative who was convicted of terrorism offenses in February 2011.The London court heard how in early 2010 Karim communicated in coded phrases from the United Kingdom with al-Awlaki in Yemen through deeply-encrypted word documents that were stealthily digitally compressed and then uploaded to pages of web hosting sites familiar to only the parties in question. The communications were relayed through Karim's brother in Yemen.
Troublingly, for Western counterterrorism officials, the documents were encrypted using software easily downloaded from the Internet. The messages appear not to have been intercepted by Western intelligence agencies. Even after finding the communications on Karim's website, it took British investigators a significant time to decipher the communications, only succeeding after they found the cipher codes and passwords in a file on his computer, illustrating how difficult it would be to track such messages in real-time. In late 2010 AQAP provided instructions in how to encrypt online communications in the second edition of its English language magazine Inspire.
What the trial did not reveal
No light was shed on al-Awlaki's operational role within AQAP in AbdulMutallab's trial, even though the Nigerian national began cooperating with investigators in January 2010, senior Obama administration officials told CNN. It's not clear how long that cooperation lasted.
By contrast, the Karim trial revealed al-Awlaki to be playing an increasingly operational role within al Qaeda.
"The question is, with the people you have, is it possible to get a package or a person with a package on board a flight heading to the US?" al-Awlaki wrote in one of the communications to Karim just weeks after the failed underwear bombing attempt.
"Our highest priority is the United States. Anything there, even on a smaller scale compared to what we may do in the United Kingdom, would be our choice," he also told Karim.