Donald Rumsfeld, the US Defence Secretary, said yesterday that terrorist cells linked to Osama bin Laden were active in 60 countries across the world including America, as the scale and complexity of the network became clearer.
The Washington government knows a great deal about how the groups associated with Mr bin Laden's al-Qa'ida organisation operate. Intricate details of structure, methods and operations have been revealed in recent trials.
Unfortunately, that has not helped America to penetrate any of the organisations or foresee last week's attacks.
The nations involved in state-sponsored terrorism according to the US State Department are Cuba, Iran, Iraq, Libya, North Korea, Sudan and Syria. Afghanistan is also branded as a prime sponsor of terrorism, but is not named on the official list because America does not recognise the Taliban as a government.
"[Bin Laden] is a prime suspect ... [in a] large, multi-headed effort that probably spans 60 countries, including the United States," Mr Rumsfeld said. "It is much bigger than one person, the problem is much broader," he said.
"There is no question" that Mr bin Laden was involved in the attacks, he said. But he acknowledged the problems. "If you do not have an army to go after or a navy to go after, you have to go after the network. And you have to then also go after the countries that are harbouring," he said. "Some of the countries that are harbouring terrorist networks do in fact have high-value targets, they do have capitals, they do have armies," he added. "What we need to do is go to the countries that we have knowledge and tell them that it has to stop and if it does not stop, we have to help stop it."
There is pressure for America to adopt different guidelines in its attempts to counter terrorism, including easing the executive order against assassinations and allowing the CIA to hire informants with criminal backgrounds.
Senator Richard C Shelby, the Republican vice-chairman of the Senate intelligence committee, said: "We have got to be a hell of a lot more aggressive."
Al-Qa'ida is a confederation of individuals and groups, based in Afghanistan and previously in Sudan. It is alleged to provide support, guidance and resources for terrorist operations, though exactly how its command structure works – or if there is a single system – is uncertain.
The nature of the al-Qa'ida organisation complicates attempts to infiltrate, understand or even find it. At one level, its operations are extremely sophisticated. They have used networks of bank accounts, satellite phones, computers, internet accounts and front companies.
But much of what it has done has been achieved through very simple methods and devices. Stolen credit cards, welfare and credit card fraud fuelled many operations, not the fabled millions of Mr bin Laden. Operatives have used sophisticated internet encryption tools, but also simple code words: "working" meant jihad, "tools" meant weapons, and "the director" was used as an alias for Mr bin Laden. Where possible, they meet in person to avoid electronic eavesdropping.
America spends about $30bn a year on intelligence. The 1993 World Trade Centre bombing, which the US has linked to Mr bin Laden, cost about $18,000.
The cell structure of the organisations around Mr bin Laden makes them hard to penetrate. Ahmed Ressam testified for the US government after being sentenced to more than 140 years in prison for his involvement in a failed plot to bomb Los Angeles international airport. He was a member of the Algerian group in the al-Qa'ida camps in Afghanistan, a large group divided into cells. Each cell had a certain area, for example, Europe. Each cell had its emir, who was in control. In his cell, there were five people.
"When you work in a group, each person knows only what he is supposed to do, not more, to preserve your secrets," Ressam said in testimony.
Stephen Gaudin, an FBI agent, gave evidence against Mohamed Rashid Daoud Al-'Owhali, a Saudi accused of bombing two American embassies in Africa in 1998. "The cell is made up of four separate sections, the intelligence section, the administration section, the planning and preparation section, and then the execution section," the agent said.
"The person who is in top of the intelligence section is in charge of the overall cell, and he assigns deputies to conduct various tasks to complete their mission."
Al-'Owhali told the FBI the training had originally been provided by another Egyptian "who was trained either by the American military or the American intelligence agencies".
The hierarchy of al-Qa'ida is what the US will want to break, and this presents further problems. "Al-Qa'ida is not a particular place, but it's a group, and it stands for the base of God's support, and bin Laden is overall in charge of al-Qa'ida," said Mr Gaudin.
US agencies have frequently claimed that Mr bin Laden has assembled a coalition of groups, and has close ties with Egyptian Islamic Jihad and links with several states, including Sudan.
Different groups work in different areas on different projects, replacing each other when one fails or is damaged.
Being linked to these organisations is not like being a member of the armed forces. Mr Gaudin said: "Mr Al-'Owhali explained to me that it's not necessary for you to actually join al-Qa'ida to actually serve with them. Al-'Owhali explained this process of joining al- Qa'ida to be taking the bayat, is what he told me. Al-'Owhali explained to me the bayat is an oath or an allegiance to bin Laden and al-Qa'ida, but I don't have to do it.
"He explained that once you take the bayat and that's it, you no longer have a choice of what missions you would like to do or want to do. If you've taken a bayat you have to do whatever is pretty much told to you. And 'Owhali explained that al-Qa'ida can assign you to both direct military roles, but also supporting roles, administrative roles, bodyguards, thing like that."
Mr bin Laden's own role is discussed mainly in terms of his charisma and the religious guidance he said.
"At the Khaldan Camp Al-'Owhali had heard statements from Osama bin Laden and these statements further solidified his religious feelings and his religious thoughts and things like that," the FBI agent said.