LONDON -- Even before Osama bin Laden's death a month ago, a young generation of would-be terrorists had turned away from the al-Qaida leader toward a new breed of brash, charismatic ideologues.
For many of these extremists, the 54-year-old bin Laden was a man of decades past – aging, longwinded and increasingly out of touch as he remained in hiding. One former jihadist compared him to a grandfather, while others have little memory of the 9/11 attacks and no interest in his history in the Soviet-Afghan war.
"We respected him ... but ... no one has seen him as much of a figure for a long time," said a 28-year-old former extremist from east London, who insisted on anonymity because of fears of reprisals. He was 18 when he began associating with extremists, he said.
Young jihadists prefer the bluntly violent rhetoric of clerics like Abu Yahya al-Libi, a Libyan-born hard-liner and rising figure within al-Qaida, and newcomer Khalid bin Abd al-Rahman al-Husaynan, whose most famous video mocks President Barack Obama's "Yes We Can" campaign slogan. Investigators fear that the hardline tone of such videos, along with a tougher atmosphere in online forums, could increase the number of young people radicalized online.
Al-Qaida itself has recognized the need to promote new voices in place of leaders such as bin Laden and his closest deputy, 59-year-old Ayman al-Zawahri. In recent months, al-Qaida's media arm, As-Sahab, has heavily promoted al-Libi, in his late 40s, and al-Husaynan, whose age isn't known.
Both offer a bullish tone and uncompromising message. In contrast, bin Laden occasionally attempted to explain his group's actions and once, in a 2006 audiotape, even discussed a long-term truce with the United States.
"The younger ideological figures can relate much better to some of the younger guys," said Aaron Zelin, who runs the Jihadology website tracking extremist activity online. "For those who are 16 to 25 now, they've grown up with a different world view."
It is the 2003 U.S.-led invasion of Iraq and the plight of Muslims in Gaza that strike a chord with young extremists now, he said, just as the Soviet-Afghan war of the late 1970s and 1980s did for bin Laden's generation.
Al-Libi in particular is feted, not least for his audacious 2005 escape from custody at the U.S. Bagram Air Base in Afghanistan. He is seen as bringing "youthful energy and a fresh perspective" to al-Qaida, said Jarret Brachman, a terrorism expert who has spent a decade monitoring al-Qaida's media operations and advises the U.S. government.
Al-Husaynan is also regarded as an influential new voice. In a video called "A Quiet Talk With Obama," al-Husaynan smiles as he mocks the president's campaign slogan, insisting, "No, Obama, you can't."
"He's so brash and punchy," said Brachman, trying to explain why young extremists look up to al-Husaynan. "A lot of the online community love to see jihadists flexing their muscles like that."
For those in the West, U.S.-born Yemeni cleric Anwar al-Awlaki has also won a devoted following, with video sermons delivered in English that reflect concerns about foreign policy and poor job prospects for young Muslims.
"I don't agree with everything he's saying, but at least he's someone who we can relate to," said a 23-year-old British engineering student with family ties to Pakistan and Afghanistan, who calls himself a former extremist. He insisted on anonymity to discuss his experiences of studying extremist clerics. "People my age never really bothered listening to people like bin Laden or al-Zawahri. They don't speak the same language as us," he said.
Several attempted attacks have showcased the powerful appeal of bin Laden's successors – and the difficulty of tracking those radicalized in their own homes, off the traditional radar.
In recent cases in Britain, two young men tried to attack after poring over jihadist videos and websites at home. One carried out a botched bombing in a restaurant, and the other constructed two suicide bomb belts and scouted a shopping mall as a target.
Roshonara Choudhry, a student jailed for 15 years after she stabbed and wounded a British lawmaker last May, told police she had listened to 100 hours of al-Awlaki's online lectures. Al-Awlaki has been tied to the 2009 shootout at Fort Hood, Texas, that left 13 dead, the attempted suicide bombing of a Detroit-bound airliner and other recent plots aimed at the U.S. and Britain.
Choudhry's case challenged orthodoxy on how terrorists become radicalized. She had no person-to-person contact with other extremists, previously considered a crucial factor, and attacked days after she finished listening to al-Awlaki.
"He explains things really comprehensively and in an interesting way, so I thought I could learn a lot from him," Choudhry told police after the attack, according to an interview transcript.
Hanif Qadir, a reformed extremist who runs a de-radicalization program in London, said the sharp tone of the new clerics resonates with young people, who also are also attracted to discussion of contemporary issues such as burqa bans in Europe.
"They feel there is someone there who is standing up to the West, standing up for what they believe, being blatant – not talking softly, but actually talking their language," he said.
In Britain, a controversial government project involving police and educators has identified 1,000 people, most aged under 25 but some as young as 7 years old, as vulnerable to the appeal of extremism. Specialists asked to steer them away from violence say many regularly browse videos by the new line of clerics.
Britain's domestic spy agency MI5 has identified the radicalization of young teens as a concern and said 15- and 16-year-olds have often been involved in plots in the U.K.
Qadir's project, the Active Change Foundation, has worked with young people flagged as a risk by parents and teachers, and with people who've served jail terms on terrorism offenses.
Youngsters swap imported DVDs and clips of beheadings stored on their cell phones, and use SMS messages or Twitter to trade addresses for jihadist websites, Qadir said. He said fewer youngsters are being recruited face-to-face, suggesting that the Internet plays an increasingly important role.
Britain's Home Office said a specialist police team, the Counter Terrorism Internet Referral Unit, has handled 1,400 complaints about extremist websites after appealing for tip-offs since Jan. 2010. With allies overseas, it has closed down about 156 sites, though that's only a small fraction of the jihadist material available online.
Mina Al-Lami, an Iraq-born academic who researches extremism at the London School of Economics, said that in addition to Internet videos from forceful new clerics, there is an increasingly aggressive tone in online forums.
Where once young people competed to post the most shocking video clips, now they round on so-called "sitters" – would-be jihadists who have yet to carry out acts of violence – goading each other to take action, and lavishing praise on those who kill themselves, she said.
Al-Lami has recently identified at least 30 people who have carried out terrorist attacks directly after being implored to do so amid heated exchanges on Arabic language jihadist forums.
She said young extremists crave a permanent successor to bin Laden who adopts the same fearless tone used by Al-Libi. They demand a new figurehead, al-Lami said, who will "threaten the West and warn that all hell will break loose in the days to come."
Paisley Dodds in London contributed to this report.