The move to place Mr al-Awlaki, 38, on a hit list was taken after a White House review concluded this year that he had moved from inciting terrorist attacks to taking part in them.
The decision is extraordinary not only because Mr al-Awlaki is believed to be the first American whose killing has been approved by a US President, but also because the Obama Administration chose to make the move public.
The Los Angeles Times reported in January that Mr al-Awlaki’s name had been placed on a top-secret list of targeted killings. In the past 24 hours, however, a handful of intelligence and counter-terrorism officials have briefed Reuters and The New York Times on the decision.
Mr al-Awlaki is believed to be hiding in Yemen, home of al-Qaeda in the Arabian Peninsula (AQAP), a rapidly growing and active affiliate of the terrorist network that orchestrated the Christmas Day plot.
The authorisation — which clears the way for Mr al-Awlaki to be captured or killed — and the decision to make it public is a high-risk strategy. The cleric has a huge following among English-speaking Muslims and his death could undermine the broader ideological battle against al-Qaeda.
Tina Foster, of the US-based International Justice Network, told The Times: “I am in shock that they would do this. It is shocking that our Government would go to these extremes, even depriving someone of their life without a legal process.”
An abortive strike that leaves a significant civilian death toll would also be a public relations disaster in the struggle against global terrorism.
“Al-Awlaki is a proven threat,” one US official said. “He’s been targeted.”
His inclusion on the hit list demonstrates how he has risen to prominence as one of the most influential and feared terrorist leaders identified by the American intelligence services. Born in New Mexico to Yemeni parents, Mr al-Awlaki spent years in America as an imam. He gained prominence after it emerged that he had been in frequent e-mail contact with Major Nidal Malik Hasan, the army psychiatrist who went on a shooting rampage in Fort Hood, Texas, in which 13 people died last November. After the Christmas Day airliner plot, US and Yemeni officials said that Mr al-Awlaki had met the suspected bomber, Umar Farouk Abdulmutallab, who tried to ignite explosives sewn into his underwear.
“The danger al-Awlaki poses to this country is no longer confined to words,” another US official said. “He’s gotten involved in plots.”
The policy of targeted killings is controversial. President Ford issued an order in 1976 banning political assassinations. Yet Congress approved the use of force against al-Qaeda after the September 11 attacks. People on the hit list are deemed to be military enemies of the US and not subject to Mr Ford’s ban.
In February Admiral Dennis Blair, Mr Obama’s intelligence chief, told Congress: “If we think direct action will involve killing an American, we get specific permission to do that.” He did not name Mr al-Awlaki as a target.
Jane Harman, the Democratic head of the House of Representatives subcommittee on intelligence, said that Mr al-Awlaki’s US citizenship made targeting him complicated. She added, however, that the cleric was “probably the person, the terrorist, who would be terrorist No 1 in terms of the threat against us”.
The move also demonstrates how Mr Obama has significantly stepped up the use of lethal force against suspected terrorists.