Overlapping responsibilities among U.S. intelligence agencies could lead to failures in assessing terror threats, experts said Monday in examining changes at the CIA and FBI since the Sept. 11, 2001, attacks.

Part of the problem stems from the continued lack of a reliable information-sharing system within the intelligence community, according to panelists led by a member of the 9/11 Commission (search) that investigated missteps leading to the attacks.

"There's a real vulnerability," former Attorney General Richard Thornburgh (search) said during the two-hour discussion — the first of eight panels hosted this summer by the commission.

"The collection of intelligence, and even its analysis, is not worth much if it's not able to be translated into a realistic threat assessment that provide guidance for the application of resources designed to prevent terrorism," Thornburgh said.

Commission member Jamie S. Gorelick (search), a former deputy attorney general, said, "We clearly need greater clarity as to who is doing what."

The panel discussions will culminate July 25 with a privately financed report card on how the government has responded to the commission recommendations issued last summer. The 10-member, bipartisan commission interviewed more than 1,000 witnesses, including President Bush, and reviewed more than 2 million documents before issuing its weighty report last July.

Monday's panel focused on reforms at the CIA and the FBI's counterterror unit to prevent future attacks. Though experts said both agencies have made progress, they agreed many more steps need to be taken.

The FBI, in particular, faces an array of challenges, including high personnel turnover and a low internal regard for counterterror analysts, said John Gannon, a former CIA official.

"Within FBI, if you are not an agent, you are furniture," Gannon said.

The panel also criticized the FBI's failed Virtual Case File computer system that was supposed to improve greatly the management of terrorism and other criminal cases.

"I think that we have been taken aback collectively by the failure of the Virtual Case File," Gorelick said. Thornburgh called the system "an unmitigated failure." An FBI spokesman declined to comment.

Despite congressional mandates, intelligence agencies still struggle to share information with each other, Gannon said.

"You don't go to work every day in the intelligence community with the idea, 'What can I share?' It's 'What can I protect?"' he said. "And that is the idiom of the business. So if you want information to be shared, it has to be very clear to people what authorities they do have to share."

Relatives of Sept. 11 victims accused the FBI and CIA of intentionally refusing to share intelligence that could have thwarted the attacks.

"The ongoing myth that the CIA's failure to communicate with the FBI was some sort of institutional failure that is readily fixable by intelligence community reforms is a notion that is whimsical at best and extremely harmful to our nation at worst," said a statement by the Sept. 11 Advocates.

Each of the seven upcoming commission panels will focus on a specific aspect of homeland defense, including protection against weapons of mass destruction, border and transportation security measures and foreign policy and diplomatic relations.