US counter-terrorism officials believe an Islamist cleric who once lived in London was the most likely suspect to have masterminded the bomb sent on cargo planes to attack Jewish groups in Chicago.
Anwar al-Awlaki, right, was born in New Mexico to Yemeni parents, and has been accused of encouraging terrorism in his sermons and writings. He is believed to have lived in London for 18 months before moving to Yemen in 2004, and is now thought to be in hiding in Yemen's rugged Shabwa or Mareb regions, an area jihadists have at times found to be a safe haven.
He is linked to multiple attempted plots against the US, by plane and by car bomb. He is also linked to one successful atrocity – the fatal shootings of 13 soldiers at Fort Hood, Texas by an American Muslim fellow soldier in November 2009.
In April of this year it was reported the Obama administration had authorised his killing. Awlaki's plots to cause carnage are one source of concern, as is his use of the internet to spread the message that Muslims should conduct violent jihad against US targets.
Yemen is home to a group calling itself al-Qaida in the Arabian Peninsula.
Last night US homeland security official John Brennan, when asked about Awlaki's suspected involvement in the cargo planes plot said: "Anybody associated with al-Qaida in the Arabian Peninsula is a subject of concern."
Terrorists in Yemen are believed to have been experimenting with turning everyday items into explosive devices. These include video cassettes and even picture frames. The director-general of MI5, Jonathan Evans, has identified Yemen as a burgeoning source for plots.
With US help, the Yemeni government has stepped up a military operation against al-Qaida sympathisers based in remote areas of the country, where anti-US feelings run high.
In addition to the terrorist plot that unfolded yesterday, the cleric is thought to be connected to the attempted car bombing in Times Square, New York and the Christmas Day attempt to explode a bomb on a flight over the US as well as inspiring the US army psychiatrist who opened fire at Fort Hood .
The suspicion of Awlaki's role in terrorist attacks against the US solidified after it was revealed he was in contact with Nidal Hassan, the US army psychiatrist who carried out the Fort Hood shooting. Hassan's first email to Awlaki asked if the cleric could justify, under Islamic law, the killing of American soldiers on US soil. The email was sent on 17 December 2008 and was intercepted by the FBI, who failed to stop Hassan before the killings 11 months later. Even after the cleric's contacts with the Fort Hood killer were known, he appeared to be operating freely in Yemen.
Awlaki went on, US officials believe, to play a role in the attempt to bomb a passenger plane in 2009.
Rashad al-Alimi, Yemen's deputy prime minister for defence and security, said Umar Farouk Abdulmutallab, the 23-year-old Nigerian who tried to detonate explosives aboard an airliner over Detroit, had gone to Awlaki's home during a trip to Yemen late in 2009.
Abdulmutallab arrived in Yemen in late August on a student visa and was last seen on 21 September. He reappeared on 5 December, and left Yemen two days later, the authorities confirmed. The deputy minister said that during his 11-week disappearance Abdulmutallab met al-Qaida leaders at a farmhouse at Rafad, in Yemen's eastern province of Shabwa. Next Awlaki was linked to Faisal Shahzad, who attempted to bomb Times Square. Shahzad, described by General David Petraeus of US central command as a "lone wolf", has reportedly told law enforcement officials that he was a "fan and a follower" of Awlaki. US officials say the militant preacher is seen as a highly influential figure in mobilising English-speaking Muslims to plan al-Qaida-style atrocities.
Yemen is just one area of concern for western counter-terrorism officials, the others being Afghanistan and Pakistan. Senior terrorist leaders are believed to be able to plan attacks and operate in areas of all three countries.
In his statement about the attacks, President Obama said Yemen president Ali Abdullah Saleh had pledged "full co-operation" to hunt down the terrorists.
"Going forward we will continue to strengthen co-operation with the Yemen government to disrupt plotting by al-Qaida in the Arabian Peninsula, and to destroy this al-Qaida affiliate.
"We will also continue our efforts to strengthen a stable, secure and prosperous Yemen so the terrorist groups do not have the time and space they need to plan attacks from within its borders."
Al-Awlaki is believed to have lived in London for 18 months before moving to Yemen in 2004.
