TRIPOLI The killing of Anwar al-Awlaki robs al Qaeda of a Web-savvy propagandist who inspired lone militants in the United States and Britain to acts of violence, helping the Pakistan-based core leadership project an image of menace even as it scattered under U.S. drone attacks.
But the death of the American of Yemeni ancestry may not hurt the group's activities in the oil-rich Gulf, home to its most ambitious branch, al Qaeda in the Arabian Peninsula (AQAP), which is trying, with uneven success, to exploit Yemen's accelerating descent into conflict.
Revenge attacks on Western targets in Yemen, possibly by his Awlaki tribe, are a distinct possibility. And the killing of a U.S. citizen by U.S. missiles fired from unmanned drone aircraft may focus public attention on moral and constitutional questions that human rights groups say are bound up with Washington's use of such remotely controlled weapons.
"Given that he was almost entirely focused on international operations against the United Sates, I doubt very much that his death will dent AQAP activity within Yemen at all," said Henry Wilkinson of Janusian security consultants.
"His death is a win for the U.S. but I don't think it's a game changer as far as AQAP's core business is concerned."
Awlaki was tied to a string of militant attacks and plots in the past three years including the killing of 13 people at the Fort Hood, Texas, military base by a U.S. army major, a failed attempt to down an airliner over Detroit, the stabbing of a British lawmaker and the involvement of a British airline employee in a plot to plant explosives in an aircraft.
Anna Murison, of Britain's Exclusive Analysis, said that "operationally it makes no odds - apart from on the recruitment side."
"AQAP are hampered in their ability to conduct transnational attacks because they do not have the large pool of Western recruits that core AQ in Pakistan used to enjoy. Awlaki could have helped them develop that base."
Awlaki's death is evidence of the increasing precision of the U.S. counter-terrorism campaign against the transnational group responsible for the Sept 11, 2001 attacks on U.S. cities.
His killing quickens the momentum of successes this year against prominent militant figures including of al Qaeda leader Osama bin Laden in May in Pakistan, the death in June of al Qaeda ally Ilyas Kashmiri, and the killing in August of Atiyah Abd al-Rahman, a Libyan and reportedly al Qaeda's then number two figure.
Bruce Hoffman, Director, Center for Peace and Security Studies at Georgetown University in the United States, told Reuters that his death first and foremost represented "a triumph for U.S. intelligence."
"The string of targeted killings of senior al Qaeda leaders this year, starting with bin Laden, through Ilyas Kashmiri and other commanders, to al Awlaki is testament to the intelligence community's unparalleled and unrivaled sophistication.
"The main impact of his killing will be the demoralization of our enemy. They can try to run, but this series of targeted killings shows that they can't hide."
It is not clear whether Awlaki held a formal role in al Qaeda, and there is debate in the counter-terrorism community over whether he was only a propagandist or whether he was an active plotter who helped to orchestrate AQAP's attacks in the West.
But what has emerged in court testimony is that he responded personally to militants who contacted him by email and encouraged them to act on their anti-Western beliefs, indicating that violence was permissible and even mandatory.
Hoffman said he believed Awlaki had a "key operational role".
John J. LeBeau, a former operational officer for the Central Intelligence Agency, told Reuters that Awlaki's involvement in the various attacks by individuals in recent years meant that Awlaki "was not merely a propagandist in the traditional sense, he actively and successfully incited people to kill Americans.
"As well, he was charismatic and enjoyed a following....That is now history, again leaving al Qaeda stuck with the aging and decidedly un-charismatic (al Qaeda leader Ayman) Zawahri as its public face."
But LeBeau added that it was an open question "whether a new Awlaki will emerge, equally effective with English-speaking recruits to enjoy relatively broad appeal via writings, and audio and video statements."
U.S. officials are worried about the emergence of so-called homegrown militants in the United States who apparently radicalise themselves by visiting Internet sites that host strongly anti-Western Islamist commentary written in English.
U.S. officials have said Washington has authorised the CIA to kill or capture Awlaki. AQAP has threatened the United States with more attacks should he be harmed.
AQAP is one of several al Qaeda offshoots that have sprung up in the past three years and are trying to attract militants from the West to their ranks, apparently encouraged by bin Laden.
Jeremy Binne, a terrorism specialist at IHS Jane's, said: "Arguably, the campaign against the US homeland was always a bit of a side show compared to AQAP's attempts to destabilise Yemen and Saudi Arabia.
"Even if it does continue to plot against the US, it does not have anyone who can tap into an international support network in the same way that he did, so his death would seem to represent a significant reduction in the group's international operational capabilities, as well as its ability to produce slick media for Anglophone audiences."
Murison of Exclusive Analysts said that Awlaki's death might complicate political calculations for Yemeni authorities including President Ali Abdullah Saleh, recently returned from medical treatment in Saudi Arabia and seeking to reimpose himself on an increasingly violent political scene.
But she added: "If the Yemenis are able to deflect blame on to the Americans enough (by denying they had any role in supplying intelligence for this), Saleh may escape unscathed from Awlaki reprisals, which would instead come against Western targets presumably.
"But Awlaki tribal reprisals would look different from AQAP terrorist reprisals, and could come in the form of kidnap demanding financial compensation for the death, rather than, say, large vehicle bombs.
Evan Kohlmann, an independent counter-terrorism consultant in the United States, said Awlaki would live on in his recorded sermons.
"He may be as much trouble dead as alive," he said.
In an article in March for an al Qaeda online magazine, Awlaki welcomed the revolts sweeping the Arab world, saying they would help rather than harm al Qaeda's cause by giving Islamists freed from tyranny greater scope to speak out.
Western and Arab officials say the example set by young Arabs seeking peaceful political change is a counterweight to al-Qaeda's push for violent militancy and weakens its argument that democracy and Islam are incompatible.
But Awlaki said: "Our mujahideen brothers in Tunisia, Egypt, Libya and the rest of the Muslim world will get a chance to breathe again after three decades of suffocation," he wrote, using a term that refers generally to Islamic guerrilla groups or holy warriors. (Reporting by William Maclean; Editing by Samia Nakhoul)