Former CIA chief James Woolsey said that during the Cold War, U.S. intelligence gathering benefited from motivated informers who wanted to see an end to the Soviet regime. However, he said that times are entirely different and the CIA alone cannot be counted on to protect the nation the way it used to do.

"In this new world we are in, although intelligence is extremely important and there are some things obviously we can do better and should, we should not count on it in the same way, particularly to give us tactical warning that we counted on intelligence [providing] during the Cold War," he said.

Mr. Woolsey, who headed the CIA from 1993 to 1995, during the Clinton administration, said that it is nearly impossible to prevent terrorism because of its secretive nature. However, he added that the CIA can adapt and American expectations of intelligence will have to adapt, too.

"What you hope to get is some things that will help you prepare better," he explained. "You need to realize that a lot of what we need to do is to improve the resilience of our own society in all sorts of ways so that even after attacks come, if they can be partially thwarted or made less effective, that those will have, to some extent, be counted as victories as well."

Mr. Woolsey said that the CIA needs more agents who speak Arabic and Persian and should focus more on rooting out militant Islamic fundraising organizations in the United States.

Others believe that the new threat terrorism poses to national security is reason to create a separate agency, other than the Federal Bureau of Investigation and the CIA, to oversee matters of domestic security.

Stansfield Turner, who headed the agency from 1977 to 1981, thinks such a new agency is needed. "I think we have a real growth area here where we will have to integrate the policeman on the motorcycle in Montana with the domestic spying done by the FBI or an MI-5 and it's going to be a very big operation and it's going to require, I think, a separate organization," he added. "This now a new task, counter terrorism, counter-intelligence and it's under one organization."

In recent months, current CIA Director George Tenet has come under criticism because his agency reported that it had "compelling evidence" that Iraqi leader Saddam Hussein had weapons of mass destruction, which have not been found.

Prior to the U.S.-led war in Iraq, the Bush administration made its case for invasion by saying Iraq posed an urgent and immediate threat. In the aftermath, there have been allegations, denied by the administration, that intelligence officials were encouraged to tailor information so that it supported the calls for war.

Mr. Turner said that political pressure is very damaging to the CIA's work. "I think the biggest problem of intelligence today is political direction from the White House and I don't know what I would do if I were George Tenet other than resign," he said.

The CIA and FBI have been criticized for not working more closely together prior to 9/11. William Webster, who has headed both agencies, said that they have done all they can to cooperate better since 9/11 and he believes the main obstacle facing intelligence today is simply outdated equipment.

"The biggest problem in cooperation between the various services on this issue in my view was Congress's failure to support the FBI in giving it the kind of technology and equipment and mainframe computers with which they could respond when the laws got changed to the inquiries from CIA and other intelligence agencies," he added. "How many of you who run businesses would operate on a 13 year old mainframe? That's what the FBI is doing today."