Twenty months ago, America was steeling itself as the twin threats of Y2K and a global Islamist conspiracy, masterminded by the renegade CIA operative Osama Bin Laden threatened to rip planes from the sky, topple Microsoft and transform the site in Jordan where John the Baptist anointed Jesus from a spiritual landmark into the killing ground of a fresh "holy war". The apocalypse, as Tuesday demonstrated, was simply delayed.
Millions of column inches in western newspapers were devoted to building this holy warrior from Saudi Arabia into a villain fit to qualify as the nemesis of America's post-cold war empire. Here was a man whose wealth - estimated at up to US$7bn - was dedicated to killing Americans "wherever they might be" as he declared in February 1998.
His ability to deliver was proven spectacularly throughout the 1990s in attacks on US property and persons. From a mountain eyrie in Afghanistan, Bin Laden presided by satellite phone over a far-flung network of supporters committed to evicting the US from its Gulf war bases in Saudi Arabia, even if it cost them their lives.
The ailing King Fahd had regularised a US military presence in the kingdom eleven years ago. This blasphemy was revenged eight years on with the split-second, timed destruction of the US embassies in Kenya and Tanzania, evidence of Bin Laden's ability to orchestrate a complex, logistical killing spree. For Osama and his followers, the US presence is tantamount to "Christian" occupation of the pilgrimage centres of Mecca and Medina, and it spurs their belief in themselves as latter-day Saracens confronting a vastly superior army of heathen Crusaders.
When the embassy bombings in Africa were identified as the fruit of his handiwork, President Bill Clinton called Osama "as dangerous as any state we face". His personal organisation, Al Qa'ida (The Base), was allegedly responsible in 1993 for the killing of 18 US troops in Somalia. The same year a handful of Bin Laden followers exploded a crude bomb at New York's World Trade Center in what now appears to have been a dress rehearsal for Tuesday's devastation.
Since 1993, his men have killed 19 Americans in Saudi Arabia, 224 civilians in east Africa and 17 sailors on the USS Cole in Aden harbour. He may have financed the Taliban's rise to power in 1996: their hospitality to him since has known no bounds. He is also reputed to have plotted the assassination of Bill Clinton and President Hosni Mubarak of Egypt and attempted (without success, so far as is known) to obtain chemical and nuclear weapons from black market suppliers in former Soviet Union states.
The evidence suggests that, far from being a nimble conspiracy of suicidal fanatics, Al Qa'ida has run rings around US intelligence simply because the latter's personnel and field skills are unequal to the task of protecting American lives and property. The families of ten US citizens killed in Nairobi in 1998 had come to the same conclusion, filing compensation claims against the government for failing to take adequate security precautions .
Neither the FBI, CIA or other agencies in America's generously funded Joint Terrorist Task Force were on the stand during the four-month trial in Lower Manhattan of four confederates of Bin Laden this spring, but perhaps they should have been.
The defendants were Arabs in a land that had moved on to new concerns under President George W Bush. At one stage, the New York Times filed agency reports on the trial, though the courthouse was only a few blocks away. Indeed, there was a sense that this was the fag end of the Clinton era.
The hunt to connect Bin Laden to the Nairobi calamity galloped parallel to Special Prosecutor Kenneth Starr's pursuit of testimony to illumine the nature of Clinton's relationship with Lewinsky. It was against this background that US military and intelligence chiefs met to determine a response to the embassy bombings, amid "intelligence reports" that there was to be a gathering of leaders of Islamist militant groups at Bin Laden's training camps at Al-Badri, near Khost in Afghanistan.
US intelligence had been aware that the camps now trained Bin Laden's soldiers for at least two years, but had taken no action for fear of estranging Pakistan and because, a generation earlier, the CIA had established the facilities to further the jihad against the Soviet Union. But what precisely had the combined CIA and FBI leadership done to pre-empt Bin Laden's two aborted assassination bids against Clinton? What efforts had been made to eliminate the Saudi, or disrupt his hostile network? Very few, it seems. The sole attempt to kill or capture Bin Laden, planned some time prior to a visit to Kabul by the then US ambassador to the UN, Bill Richardson, in April 1998, had been aborted due to the expected number of US and Afghan casualties. Was fear of casualties a convincing enough reason for America's Praetorian Guard to allow a committed assassin to remain on the loose, or was it fear of public exposure, or something more unthinkable? Blame-shirking, it seemed, had become the guiding principle of the CIA and the presidency.
On August 20, at 6.30am, as Lewinsky lay dreaming of the detail she would reveal to the Grand Jury later that morning, 70-100 Tomahawk missiles were launched at targets in Khartoum, Sudan and near Khost. The missiles were designed to cause maximum damage over a wide area, rather than take out a single pinpointable target. Six of his men perished in the raid, but Bin Laden escaped.
The enemy that US intelligence confronted in Al Qa'ida was neither well trained nor particularly astute. One day after the Nairobi bombing, the first suspect, Mohammed Sadiq Odeh, was arrested in Karachi, having travelled from Kenya with a passport whose photo did not quite match his face. Following the evasion techniques drilled into Al Qa'ida's volunteers in Sudan - which include dressing in western clothes and wearing cologne - Odeh had shaved his beard off, making him an easy mark for immigration officials.
Similarly, US interception of e-mail, fax and satellite phone messages between Bin Laden and his overseas associates revealed an astonishingly naive grasp of spycraft. In one fax, the Saudi was referred to by his US and Irish pseudonyms - "Mr Sam" and "Mr O'Sam" - and repeatedly warned to beware of "an opposition company called the Food and Beverage Industry, based in the US".
Though Washington threatened blue murder from the wings after Khost, on-the-ground relations with the Taliban displayed a remarkable reticence. Yes, a $5m reward was posted and, yes, the State Department made it abundantly clear that diplomatic recognition of Afghanistan's rulers would depend upon their handing over Bin Laden. But there was a marked reluctance to take any more direct action, whether by challenging the Taliban to reveal his whereabouts, or launching a cross-border raid to take him forcibly. Wherever he was hiding, the Afghan whispering gallery guaranteed it would not remain secret for long.
Why did Washington fail to mount a snatch operation or an outright assassination attempt? Certainly there was the risk that US agents would be killed, or captured and presented to the world through the whetted lens of the media. But an operation was still feasible with cut-outs, perhaps Arabs affiliated with Israel's Mossad.
For one reason or another, the US combined intelligence forces made killing Osama as inconceivable as Tuesday's meltdown in Manhattan.
Michael Griffin is author of Reaping the Whirlwind: the Taliban movement in Afghanistan (Pluto Press, £19.99)