To revive their flagging movement, al-Qaeda decided to take its fight to the West, "the far enemy", but this caused a rift with other militant movements who feared US military power would ultimately destroy them.
On Sunday, al-Qaeda leader Osama bin Laden released an audio tape accusing the West of mounting a "Crusader war" on Muslim nations.
Gerges, who holds the Christian Johnson Chair in International Affairs and Middle Eastern Studies at New York's Sarah Lawrence University, believes bin Laden may be growing desperate.
Aljazeera.net: What are we to understand from Osama bin Laden's message about a crusader war against Muslims?
Fawaz Gerges: Bin Laden is desperately trying to capitalise on America's and the West's woes in Iraq and elsewhere to convince young Muslims that the West is waging a "crusader war on Islam", and that they should resist the new imperial crusade militarily.
For bin Laden, the current struggle is more than political or economic; it is existential and civilisational. His mission, as he clearly states, is to incite young Muslims and remind them of the stakes involved in this global conflict.
He sounds deeply disappointed that his messages have fallen on deaf ears. The caravan of jihad has left him behind, and it is moving in a dramatically different direction than he had expected. He feels an urgent need to remind his followers and the Muslim community that he is still alive, that he exists.
But the truth is that there are few takers for his civilisational war. Neither Iraqis nor Palestinians are willing to wage a war on bin Laden's behalf; nor do they subscribe to his vision. They have much more limited goals than bin Laden's ambitious and convoluted rhetoric.
In your book you state that the 9/11 attacks were bin Laden's idea but that other jihadi leaders disagreed with him. Why did they remain silent?
9/11 was carried out by a tiny faction - al-Qaeda - which represents a minority within the jihadi movement and its strategies have been vehemently criticised and opposed by religious nationalists. They preferred to concentrate on changing the Muslim world rather than taking the fight global.
The majority of lieutenants decided to go their own ways because they disagreed with the merger between the Egyptian Islamic Jihad, Ayman al-Zawahiri's organisation, and al-Qaeda.
Some of them in internal correspondence wrote to al-Zawahiri and said "listen we'll go on our own way but we will never air our dirty laundry in public, we will never try to discredit you".
I think this is a kind of a secret universe, a universe that does not function according to rational means. They have a deep sense of loyalty and brotherhood towards each other.
Why did bin Laden and al-Qaeda decide to focus on the West?
The catalyst that turned bin laden against the far enemy (The Christian West) was the American military intervention in the Gulf war in 1991 and the permanent stationing of US troops in Saudi Arabia.
You begin your book by critiquing the 9/11 Commission report and stating that the United States sees the jihadi movement as monolithic.
I think the 9/11 Commission report focused on the criminal investigation. It presented a partial portrait of how the 9/11 conspiracy unfolded: Trying to piece together the various threads of the plot such as when the orders were given, who gave them, who were the leading conspirators behind the plot. I think the Americans wanted to know who did what.
So the 9/11 report started with the micro details and made very sweeping generalisations not about the conspiracy itself but about the nature of the threat that the United States faced.
In other words, the report stopped short of illuminating the big historical and sociological questions of how and why jihadi movements decided to attack the United States. It lumped indirectly the jihadi movement with the Islamist movement as a whole.
I think it was highly dangerous to make sweeping generalisations and to lump all jihadis together with al-Qaeda as well as the Islamist movement.
Why do you consider that to be dangerous?
The US is no longer facing a tiny dangerous faction within the Islamist movement that is al-Qaeda. The US faces now an ideological enemy which encompasses all jihadis, local jihadis and trans-national jihadis and even radical Islamists.
In many ways this basically sets the US on a highly dangerous track because it's one thing to say that the US faces al-Qaeda which is a highly dangerous enemy and it's another to say that the US faces an ideological threat which encompasses all jihadis and even all Islam.
It changes the nature of confrontation and basically convinces Americans who know very little about the nuances and differences between jihadis and the Islamists that somehow we're facing what I call an existential threat, a strategic threat. And this is not true.
You speak of other militant groups. Are Lebanon's Hezbollah and the Palestinian Hamas part of the jihadis movement?
Yes, however, Hezbollah and Hamas are the radical Islamists who basically focus their energy and militancy on the [Israeli] occupation. They do not believe in the expansion of jihad outside the Arab-Israeli conflict.
How central an issue is the Israeli-Palestinian conflict to these jihadi movements?
In the book, I show that the overwhelming majority of clerics, Islamists and civil society leaders were opposed to the 9/11 attacks.
But when it comes to the question of Palestine the opposite is true. The overwhelming majority of clerics, opinion makers, and religious leaders look at what Hamas and Islamic Jihad are doing against the Israeli occupation as legitimate forces of resistance.
The Israeli six day war in 1967 was really one of the pivotal factors in the rise of the Islamist and jihadi movement. No doubt about it. Palestine has inspired generations of Arab and Muslim activists and radicals and jihadis and militants ... even secular militants.
Has the war in Iraq strengthened al-Qaeda?
Well, I don't think the war in Iraq has strengthened al-Qaeda. I think what the war in Iraq has done is to create a new generation of jihadis who basically subscribe to a similar ideology to that of al-Qaeda.
I think the American war in Iraq has played into the hands of al-Qaeda's trans-national ideology on global jihad. In many respects, Iraq is slowly and gradually replacing Afghanistan as a recruiting tool and ground for jihadi action.
Let's remember though that the overwhelming majority of fighters in Iraq are Iraqi nationalists or Islamists who are trying to end the US occupation in Iraq.
But powerful factions of jihadis who are lead by [Abu Musab] al-Zarqawi have basically received a great deal of public and popular support as a result of the war that has raged in Iraq for the past three years.
So in many ways, yes it has supplied ammunition to the ideology of global jihad.
And of course it has deepened and widened anti-Americanism throughout Arab and Muslim lands. It silenced moderates who basically went on the offensive against the ideology of global jihad after 9/11.
What is the best way to defeat al-Qaeda?
The American war against al-Qaeda cannot and will not be won on the battlefield. The US is not facing a conventional army. This is an unconventional war and I think in many ways al-Qaeda is totally highly adaptable and dynamic.
The only way for the US and the international community to win this war is by creating coalitions and alliances with Arab and Muslim societies, not just counter-insurgency tactics.
The US must really endeavour to address the legitimate grievances of the floating middle and Arab and Muslim public opinion and create alliances by addressing regional conflicts like the Palestinian predicament.
It does this by keeping a healthy distance from Arab and Muslim dictators and by building bridges with the largest constituency in the Arab Muslim world - Arab and Muslim youth.