Attributed to the terrorist organization al-Qaeda in the Arabian Peninsula (AQAP), the act was undertaken by 23-year-old Nigerian national Umar Farouk Abdulmutallab using chemical explosives sewn to his underwear.

[5] AQAP leader Anwar al-Awlaki, who reportedly inspired Abdulmutallab and "masterminded" the attack,[6] was killed two years later as the target of a drone strike in Yemen.

On December 16, 2009, Abdulmutallab visited the KLM Royal Dutch Airlines office in Accra, Ghana and paid $2,831 in cash for a Lagos-Amsterdam-Detroit round-trip ticket, with a January 8, 2010, return date.

[30][31] When the plane landed, Abdulmutallab was handed over to U.S. Customs and Border Protection (CBP) officers, and taken into custody for questioning and treatment of his injuries in a secured room of the burn unit of the University of Michigan Medical Center in Ann Arbor.

[46] For the 2004–05 academic year, Abdulmutallab studied at the San'a Institute for the Arabic Language in Sana'a, Yemen, and attended lectures at Iman University.

[47][48] He began his studies at University College London in September 2005,[49] where he was president of the school's Islamic society in 2006 and 2007, during which time he participated in, along with political discussions, such activities as martial arts and paintballing.

[54][55] In May 2009, Abdulmutallab tried to return to Britain, supposedly for a six-month "life coaching" program at what the British authorities concluded was a fictitious school; accordingly, his visa application was denied by the United Kingdom Border Agency.

[43] By September, he routinely skipped his classes at the institute and attended lectures at Iman University, which intelligence officials from the United States suspected to have links to terrorism.

[65][66][67] A number of sources reported contacts between Abdulmutallab and Anwar al-Awlaki, the late Muslim lecturer and spiritual leader who the U.S. accused as a senior al-Qaeda talent recruiter and motivator.

[70][72] CBS News reported that the two had communicated in the months before the bombing attempt, and other sources have said that at a minimum, al-Awlaki was providing spiritual support for Abdulmutallab and the attack.

[76][77] Yemen's Deputy Prime Minister for Defense and Security Affairs, Rashad Mohammed al-Alimi, said Yemeni investigators believe the suspect traveled in October to Shabwa, where he may have obtained the explosives and received training.

[81] Al-Awlaki released a tape in March 2010, in which he said, in part: Beginning December 18, 2009, President Obama authorized attacks on suspected Al-Qaeda bases in Yemen.

[87][88] On January 24, an audio tape said to be from Osama bin Laden praised the bombing attempt and warned of further attacks against the United States, but did not claim responsibility for it.

[93] But U.S. Representative Jane Harman (D-Calif.), Chairman of the House Homeland Security Subcommittee on Intelligence, Information Sharing, and Terrorism Risk Assessment, said the following day that a federal official briefed lawmakers about "strong suggestions of a Yemen-al Qaeda connection" with the suspect.

[95][96] In reaction to suggestions that the U.S. launch a military offensive against the alleged terrorists' sanctuary in Yemen, The Washington Post noted that Yemeni forces equipped with U.S. weapons and intelligence had carried out two major raids against AQAP shortly before the bombing attempt, and that the terror group may have lost top leaders in a December 24, 2009 airstrike.

[97] On March 24, 2011, the Associated Press reported that before Abdulmutallab set off on his mission, he visited the home of al-Qaeda manager Fahd al-Quso to discuss the plot and the workings of the bomb.

"[99] Jasper Schuringa, who was en route to Miami, Florida, for a vacation, stopped Abdulmutallab from causing too much damage and received burn injuries in the process.

[123] ABC News cited a government test indicating that 50 grams (1.8 oz) of PETN can blow a hole in the side of an airliner, and posted photos of the remains of Abdulmutallab's underwear and explosive packet.

[118][119] On January 7, 2010, James L. Jones, the National Security Advisor, said Americans would feel "a certain shock" when a report detailing the intelligence failures that could have prevented the attack would be released that day.

"[125] On April 6, 2010, it was reported that President Obama had authorized military action to kill Anwar al-Awlaki, the Muslim cleric accused of being a Yemen-based al-Qaeda commander behind the plot.

[130] Members of the Second Chamber (Lower House) of the Dutch parliament demanded an explanation from Minister of Justice Hirsch Ballin, asking how the suspect managed to smuggle explosives on board, despite Schiphol's reportedly strict security measures.

[141] When asked about his decision to prosecute Abdulmutallab in federal court rather than have him detained under the law of war, U.S. Attorney General Eric Holder defended his position, saying that it was "fully consistent with the long-established and publicly known policies and practices of the Department of Justice, the FBI, and the United States Government as a whole," and that he was confident that Abdulmutallab would be successfully prosecuted under the federal criminal law.

[37] The TSA detailed several of these measures, including a restriction on movement and access to personal items during the last hour of flight for planes entering U.S. airspace.

[143][144] Under new rules prompted by the incident, airline passengers traveling to the U.S. from 14 nations would undergo extra screening: Afghanistan, Algeria, Cuba, Iran, Iraq, Lebanon, Libya, Nigeria, Pakistan, Saudi Arabia, Somalia, Sudan, Syria, and Yemen.

[149] However, in spite of the extra measures said to have been put in place to prevent a follow-up attack, Stuart Clarke, a photoreporter from the British newspaper Daily Express, claimed to have smuggled a syringe containing fluid, which could have been a liquid bomb detonator onto another plane.

[12][121] Four days after the attack, Obama said publicly that Abdulmutallab's ability to board the aircraft was the result of a systemic failure that included an inadequate sharing of information among U.S. and foreign government agencies.

"[153] He ordered that a report be delivered detailing how some government agencies had failed to share or highlight potentially relevant information about the suspect before he allegedly tried to blow up the airliner.

Obama said he would meet with security officials and specifically question why Abdulmutallab was not placed on the U.S. no-fly list, despite the government having received warnings about his potential al-Qaeda links.

[156][157][158] On May 7, 2012, American officials claimed that they had thwarted another Al Qaeda plot that would have targeted a civilian passenger plane not unlike Northwest Airlines Flight 253.

[159] American officials stated that the attack would have involved a more sophisticated bomb, also planted in undergarments, and would have been deployed near the anniversary of the killing of Osama Bin Laden.