The commission investigating the Sept. 11 attacks found widespread failures of imagination, policy, capabilities and management.

Their findings include:

Leaders failed to understand the gravity of the threat from Usama bin Laden and his Al Qaeda network. Terrorism was not the overriding national security concern for the U.S. government under the administrations of either President Bill Clinton or President Bush before the Sept. 11 attacks.

Before Sept. 11, 2001, the United States tried to solve the Al Qaeda problem with the capabilities it had used in the last stages of the Cold War and its immediate aftermath. These capabilities were insufficient.

The FBI did not have the capability to link the collective knowledge of agents in the field to national priorities, and other domestic agencies deferred to the FBI. Federal Aviation Administration capabilities were weak. The CIA had minimal capacity to conduct paramilitary operations with its own personnel and needed to improve intelligence collection from human agents.

The U.S. government did not find a way to pool intelligence and use it to guide planning and assignment of responsibilities for joint operations involving entities as disparate as the CIA, the FBI, the State Department, the military and the agencies involved in homeland security.

Starting in 1997, the U.S. government tried without success to use diplomatic pressure to persuade Afghanistan's Taliban regime to stop sheltering Al Qaeda and to expel bin Laden to a country where he could face justice.

There was a lack of military options, which military officials blamed on a dearth of actionable intelligence, to strike at bin Laden and Al Qaeda.

The intelligence community struggled throughout the 1990s up until 9/11 to find out about transnational terrorism. "The combination of an overwhelming number of priorities, flat budgets, an outmoded structure and bureaucratic rivalries resulted in an insufficient response to this new challenge."

Problems at the FBI included limited intelligence collection and strategic analysis capabilities, a limited capacity to share information, insufficient training and inadequate resources.

Protecting borders was not a national security issue before 9/11 and neither the State Department nor the Immigration and Naturalization Service were ever considered full partners in a national counterterrorism effort.

Aviation security was "permeable" and easy for 9/11 hijackers to navigate. Once aboard, hijackers encountered aircraft personnel who were trained to be non-confrontational in the event of a hijacking.

The origin of the money that paid for the 9/11 attacks is still unknown.

Emergency response was life-saving, but in New York was hampered by problems with command and control and with internal communications.

Congress and the executive branch of government responded slowly to the rise of transnational terrorism as a threat to national security.

Killing or capturing bin Laden would not end terror: "his message of inspiration to a new generation of terrorists would continue."

(Source: 9/11 Commission Report)