Osama Bin laden released a video message shortly after US bombing started
A new book about Osama Bin Laden - the radical Islamist accused of masterminding the September attacks against America - provides a detailed account of his life and the global network he now runs.
In 1997 Peter Bergen went to Afghanistan with Peter Arnett to interview Osama Bin Laden for CNN.
Since then he has continued to pursue his prey in different ways, interviewing Bin Laden's friends and enemies, reading widely and building up a formidable amount of information about the man and his group, al-Qaeda.
Mr Bergen's book, Holy War Inc: Inside the Secret World of Osama Bin Laden, is thus the result of several years of research.
Eye for detail
It was completed in August of this year, then revised and published with breath-taking speed following the events of 11 September. It is not, therefore, an "instant book" in the usual sense.
The book's strength is that it is based on extensive interviews in many of the key locations - in Afghanistan and Pakistan, in the Middle East, in the United States and Europe. Like all good journalists, Bergen has an eye for detail and a sense of place.
Many will read this book in an effort to understand Osama Bin Laden, the man whose face now fills so many newspaper pages and television screens. Wisely, Bergen offers few theories, preferring to pin down elusive facts.
He rejects the notion that Bin Laden had a playboy youth. He was the pious son of a Yemeni father and a Syrian mother. His father, Mohammed, was a self-made man who had migrated to Saudi Arabia and built up a successful construction company.
Bin Laden's mentors
He was only 10 years old when his father died in a plane crash. Bergen speculates, plausibly, that in later life two or three men played the role of father figure.
One was Abdullah Azzam, the charismatic Palestinian who became his teacher at King Abdel-Aziz University in Jeddah, where Bin Laden studied economics and public administration. Other sources have suggested he studied engineering.
Azzam then became his mentor in Afghanistan, when the two men joined the army of "Arab Afghans" who went there in the 1980s to fight the country's Soviet occupiers.
For Bin Laden, still in his early 20s, this was a formative experience. The eventual Soviet withdrawal convinced him of the "myth of superpower".
After Azzam's mysterious assassination, he drew closer to a radical Egyptian Islamist, Ayman al-Zawahiri. Bergen suggests Zawahiri's Jihad group virtually took over al-Qaeda, the organisation Bin Laden formed in 1989.
Hatred of America
His subsequent career, from his brief homecoming to Saudi Arabia, through his exile in Sudan, to his return to Afghanistan in 1996, was a process of constant radicalisation.
A turning-point was 7 August 1990, when American troops first began arriving in Saudi Arabia as part of Operation Desert Storm, the war to drive Iraqi forces from Kuwait.
Bergen believes it was no coincidence that the bombing of the two US embassies in East Africa took place on 7 August eight years later.
Forcing the Americans out of the Arabian peninsula has remained a driving obsession. Other issues - Iraq, Palestine, Kashmir, Bosnia - have contributed to his hatred of America. But it is the fate of his native land which is at the root of Bin Laden's global jihad.
Among much other information, Bergen tells us:
Peter Bergen's book, Holy War Inc, is published in Britain by Weidenfeld & Nicolson and in the United States by The Free Press