But nearly three weeks later, as the sheer extent of America's unpreparedness and vulnerability comes into better focus, one other conclusion is inescapable. The September 11 massacre resulted from a fantastic failure on the part of the United States government to protect its citizens from an act of war. This failure is now staring us in the face and, if the errors are to be rectified, it is essential to acknowledge what went wrong.
Two questions come to mind: how was it that the Osama Bin Laden network, known for more than a decade, was still at large and dangerous enough this autumn to inflict such a deadly blow? Who was responsible in the government for such a failure of intelligence, foreign policy and national security? These questions have not been asked directly, for good reasons.
There is a need to avoid recriminations at a time of national crisis. But at the same time, the American lack of preparedness that Tuesday is already slowing the capacity to bring Bin Laden to justice by constricting military and diplomatic options. And with a president just a few months in office, criticism need not extend to the young administration that largely inherited this tattered security apparatus. Whatever failures of intelligence, security or diplomacy exist, they have roots far deeper than the first nine months of this year. When national disasters of unpreparedness have occurred in other countries - say, the invasion of the Falkland islands - ministers responsible have resigned. Taking responsibility for mistakes in the past is part of the effort not to repeat them. So why have heads not rolled? The most plausible answer is that nobody has been fired because this attack was so novel and impossible to predict that nothing in America's security apparatus could have prevented it. The only problem with this argument is that it is patently untrue. Throughout the Clinton years, this kind of attack was not only predictable but predicted. Not only had Bin Laden already attacked American embassies and warships, he had done so repeatedly and been completely frank about his war. He had even attempted to destroy the World Trade Center in 1993. Same guy, same building. To say that nobody could have anticipated this type of attack is simply to say that US intelligence wasn't good enough to have found it out.
How prominent were the warnings of the danger of Islamic terrorism in the 1990s? Here's one: "The crater beneath the World Trade Center and the uncovering of a plot to set off more gigantic bombs and to assassinate leading political figures have shown Americans how brutal these extremists can be." This was written by Salman Rushdie in The New York Times in 1993. Did the Clinton administration overhaul its intelligence and defence priorities in response to the 1993 warning? No. No effort was made to co-ordinate the mess of agencies designed to counter terrorism - the FBI, the CIA, the Pentagon, the State Department, the airlines, local law enforcement, the Coast Guard. No effort was made to recruit more spies who could speak Arabic or go undercover to pre-empt such attacks. Under the Clinton administration a law was passed making it more difficult for America to use spies who had sleazy or criminal pasts - the kind needed to infiltrate Bin Laden's cells. The debacle of the Somalia expedition in 1992 and 1993 - which led to US special forces being humiliated - dramatically chilled the military's willingness to use such Delta Force units in action again. This occurred despite the fact that aggressive use of such forces was critical to any successful effort to regain the initiative against terrorism. In a remarkably revealing and overlooked article in last week's New Yorker, Joe Klein argues that "there seems to be near-unanimous agreement among experts: in the 10 years since the collapse of the Soviet Union almost every aspect of American national security policy - from military operations to intelligence-gathering, from border control to political leadership - has been marked by . . . institutional lassitude and bureaucratic arrogance".
The decision to get down and dirty with the terrorists, to take their threat seriously and counter them aggressively, was simply never taken. Many bear the blame for this: Warren Christopher, the clueless, stately former secretary of state; Anthony Lake, the tortured intellectual at the National Security Council; General Colin Powell, whose decision to use Delta Force units in Somalia so badly backfired; but, above all, former president Bill Clinton, whose inattention to military and security matters now seems part of the reason why America was so vulnerable to slaughter.
Klein cites this devastating quote from a senior Clinton official: "Clinton spent less concentrated attention on national defence than any other president in recent memory. He could learn an issue very quickly, but he wasn't very interested in getting his hands dirty with detail work. His style was procrastination, seeing where everyone was, before taking action. This was truer in his first term than in the second, but even when he began to pay attention he was constrained by public opinion and his own unwillingness to take risks."
It is hard to come up with a more damning description of negligence than that. Clinton even got a second chance. In 1998, after Bin Laden struck again at US embassies in Africa, the president was put on notice that the threat was deadly. He responded with a couple of missile strikes against Afghanistan and Sudan, some of which missed their targets and none of which seriously impacted on Osama Bin Laden.
Clinton's own former defence secretary, John Deutch, wrote in The New York Times that August: "We must insist on superior intelligence that will warn of potential terrorist actions. We must insist on tough and prompt responses, and on developing an effective capability to manage the consequences of these acts when they occur. In general, public and private experts have concluded that our country is not fully prepared to act effectively on these matters." Clinton largely ignored the warning. In The Washington Post that August, the following prescient words were written by L Paul Bremer III, the former anti-terrorism chief in the Reagan administration: "The ideology of such groups [as Bin Laden's] makes them impervious to political or diplomatic pressures. They hate America, its values and its culture and proudly declare themselves to be at war with us. We cannot seek a 'political solution' with them." Bremer then set out a list of what the US should do: "Defend ourselves. Beef up security around potential targets here and abroad, especially 'softer' targets such as American businesses overseas. Attack the enemy. Keep the pressure on terrorist groups. Be as systematic and relentless as they are. Crush Bin Laden's operations by pressure and disruption. The US government should order further military strikes against the remaining terrorist training camps in Afghanistan and Sudan. The government, further, should announce a large reward for Bin Laden's capture - dead or alive. This might work and at the least would exacerbate the paranoia common to all terrorists."
Sound familiar? It's exactly what is being done now, three years too late, with no element of surprise, and with far from adequate human intelligence.
This brings Bremer to the most critical point in his recommendations: "Improve our intelligence operations. Effective counterterrorism depends on good intelligence . . . We must pre-empt attacks before they happen. This requires improved co-ordination of intelligence collection. While it is difficult, we should expand the use of deep-cover agents on the ground to infiltrate organisations." None of this happened. The CIA's feckless record went uncorrected.
Perhaps the most farsighted critic was a man called Reuel Marc Gerecht, a former case officer in the CIA's clandestine service and the author, under the pseudonym Edward Shirley, of a book called Know Thine Enemy: A Spy's Journey into Revolutionary Iran.
In The Atlantic Monthly this summer, he emphasised the need for trained spies to go underground in the Muslim world of Afghanistan and Pakistan if the West were ever to get adequate intelligence on Bin Laden's operation. Gerecht also reported the following devastating fact: "Robert Baer, one of the most talented Middle East case officers of the past 20 years (and the only operative in the 1980s to collect consistently first-rate intelligence on the Lebanese Hezbollah and the Palestinian Islamic Jihad), suggested to headquarters in the early 1990s that the CIA might want to collect intelligence on Afghanistan from the neighbouring central Asian republics of the former Soviet Union.
"Headquarters' reply: too dangerous, and why bother? The cold war there was over with the Soviet withdrawal in 1989. Afghanistan was too far away, internecine warfare was seen as endemic, and radical Islam was an abstract idea.
"Afghanistan has since become the training ground for Islamic terrorism against the United States, yet the CIA's clandestine service still usually keeps officers on the Afghan account no more than two or three years."
If you want to know why it seems unlikely that America knows enough about Bin Laden's whereabouts to mount an immediate attack today, then re-read those sentences. This is an intelligence failure of colossal proportions.
What happened to the man who presided over that massive failure? George Tenet, director of the CIA since 1997, is still in his job.
Not everyone in Washington was asleep at the switch. In response to the African embassy bombings, a national commission on terrorism was set up to propose changes. It was headed by a top-notch group of former officials and got plenty of attention. The panel argued that America was extremely vulnerable to a huge attack by a group such as Al-Qaeda, and recommended better espionage, more Arabic-speaking spies, better intelligence-sharing between the FBI and the CIA, wider wiretapping, and much of what is now on the table. The report was even prescient enough to have a picture of the World Trade Center on its cover.
But the report died the death of a thousand quibbles. Civil liberties advocates complained about a threat to individual freedom. James Zogby, the president of the Arab-American Institute, said the proposals were like "the darkest days of the McCarthy era". A writer in the online magazine Salon described the warnings of a domestic attack as "a con job with roughly the veracity of the latest Robert Ludlum novel". The CIA opposed lowering its squeaky-clean standards for spies, and the FBI was desperate, under Clinton, to avoid any Reagan-like dirty tricks in its operation.
When the report came to Congress, it was attacked by Senator Patrick Leahy of Vermont, who distrusted the CIA and wanted to avoid what he called "risks to civil liberties we hold dear". The proposal picked up momentum after the attack in Aden on the USS Cole last October, but was so watered down by the end of the legislative process that it was virtually useless. The Clinton administration did next to nothing to rescue it.
Clinton's former national security adviser, Sandy Berger, defended the president's record to Klein in The New Yorker. He argued that, after the embassy bombings, there was a concerted effort to find and kill Bin Laden, and that the cruise missile in Afghanistan missed its target by an hour, after which Bin Laden disappeared from view. Anonymous Clinton officials also blame the former treasury secretary Robert Rubin for resisting measures to cut off Bin Laden's financing, and to use cyber warfare to crack down on terror money networks.
Others blame the FBI: "[The FBI's] standard line was that Bin Laden wasn't a serious domestic security threat," one source told Klein. "They said that he had about 200 guys on the ground and they had drawn a bead on them." But whatever the nuances of blame here, it is clear that nobody from the top intervened, imposed order and reorganisation.
Earlier this year, yet another report, chaired by the respected former senators Gary Hart and Warren Rudman, came to yet another definitive conclusion that America was vulnerable. They made exactly the same recommendations that are now finally being implemented; the report was well advertised and disseminated in the press - and still nothing was done.
Hindsight is easy, of course. In the halcyon and feckless climate of the 1990s, it would have required real political leadership to dragoon various stubborn government agencies into a difficult reorganisation to counter terrorism. It would have been extremely hard to persuade a sceptical public and a prickly civil liberties lobby that vast new powers were necessary to prevent catastrophe. This much is true. But it's also true that there were several unmistakable attacks on America by the very forces that have now launched a war. It is also true that many, many people recognised this and were brave enough to warn about it.
In August 1998, Milton Bearden, the former CIA chief in Pakistan and Sudan, wrote in The New York Times: "The case against Osama Bin Laden is clear-cut. Through his self-proclaimed sponsorship of terrorism against the United States, he has, in effect, declared war on us." In July 1999, William Cohen, Clinton's defence secretary, wrote in The Washington Post: "In the past year, dozens of threats to use chemical or biological weapons in the United States have turned out to be hoaxes. Someday, one will be real".
Whatever excuses members of Clinton's administration may have, they cannot trot out the excuse of not having been warned. We were all warned. We just preferred to look the other way. It is clear that there are many in the American government who, while not being "guilty men" in sympathising with, and appeasing, the enemy were, at the very least, "negligent men". They deserve some sympathy. They were imperfect human beings in a world where September 11 was still an abstract. But we pay our politicians to assess the possibility of an actual threat. That's what they are there for. And, on that critical task, they failed.
If the security manager of a nuclear power plant presides over a massive external attack on it, then it's only right that he should be held responsible, in part, for what happened. More than 6,000 families are now living with the deadly consequences of the negligence of the government of the United States. There is no greater duty for such a government than the maintenance of national security, and the protection of its own citizens.
When a senior Clinton official can say of his own leader that he "spent less concentrated attention on national defence than any other president in recent memory", and when this administration is followed by the most grievous breach of domestic security in American history, it is not unreasonable to demand some accounting.
Clinton is not alone. The list of people who resisted or thwarted the measures needed to have avoided this catastrophe are many. They reach back to president George Bush Sr, who balked at removing Saddam Hussein from power at the end of the Gulf war, thus leaving the single most dangerous abetter of international terrorism at large on the world stage.
They include Bush and Clinton officials who failed to see the danger in the vacuum left in Afghanistan after the successful insurgency against the Soviets. They include senators, congressmen, lobbyists, civil liberties advocates and journalists - all of whom failed to see the danger. Few of us are free from blame, but the most blame must surely be attributed to the top. We thought for a long time that the Clinton years would be seen, in retrospect, as a mixed blessing. He was sleazy and unprincipled, we surmised, but he was also competent, he led an economic recovery, and he conducted a foreign policy of multilateral distinction.
But the further we get away from the Clinton years, the more damning they seem. The narcissistic, feckless, escapist culture of an America absent without leave in the world was fomented from the top. The boom at the end of the decade turned out to include a dangerous bubble that the administration did little to prevent.
The "peace-making" in the Middle East and Ireland merely intensified the conflicts. The sex and money scandals were not just debilitating in themselves - they meant that even the minimal attention that the Clinton presidency paid to strategic military and intelligence work was skimped on.
We were warned. But we were coasting. And the main person primarily entrusted with correcting that delusion, with ensuring America's national security - the president - was part of the problem.
Through the dust clouds of September 11, and during the difficult task ahead, one person hovers over the wreckage - and that is Bill Clinton. His legacy gets darker with each day.
