In September 2007, on the sixth anniversary of 9/11, a bespectacled Saudi cleric settled into his chair at MBC, an Arab satellite channel, to discuss al-Qaeda. His presence immediately stirred the attention of viewers who recognised Salman al-Awdah as one of Osama bin Laden's longtime mentors. What he said in that interview shocked al-Qaeda and its supporters.

"How much blood has been spilled? How many innocent children, women, and old people have been killed [...] in the name of al-Qaeda?" he asked. Reading an open letter to "brother Osama", he dissociated himself from al-Qaeda. It came just four months after another of al-Qaeda's chief ideologues, an imam called Dr Fadl, expressed similar views in a letter sent to Arab newspapers from his jail cell in Egypt.

This public spat between al-Qaeda's leaders quickly fuelled suggestions that the movement was imploding under the weight of internal dissent. They prompted author Peter Bergen, who interviewed bin Laden in 1997, to label these developments as "the unravelling" of al-Qaeda. Lawrence Wright, who also profiled Dr Fadl for the New Yorker this year, was similarly confident that his letter would deal a fatal blow to the movement, branding Fadl an al-Qaeda apostate.

But that optimism belies the terror group's history and ignores circumstances that first gave rise to it almost 20 years ago, suggesting that al-Qaeda is likely to emerge from this storm unscathed. Perhaps the best illustration of this is the story of a hugely-influential Islamist militant named Abdullah Azzam.