Former Vice President Al Gore (search) met with the Sept. 11 panel privately Friday, a day after President Clinton (search) told commissioners that intelligence wasn't strong enough to justify a retaliation against Al Qaeda (search) for the 2000 bombing of a Navy ship.

Gore met with the 10-member bipartisan commission in a three-hour meeting it described as candid and forthcoming. "We thank him for his continued cooperation with the commission," the panel said in a statement.

On Thursday, the commission interviewed Clinton behind closed doors for nearly four hours after the conclusion of national security adviser Condoleezza Rice's (search) public testimony, broadcast live on national television.

Bob Kerrey, a former Democratic senator from Nebraska and now a member of the commission, said Friday on ABC's "Good Morning America" he believes Clinton should have been more aggressive in going after Al Qaeda following the ship attack.

"I think he did have enough proof to take action," Kerrey said. "That's a difference of opinion."

A person familiar with the session said Clinton told the commission he did not order retaliatory military strikes after the bombing of the USS Cole (search) in October 2000 because he could not get "a clear, firm judgment of responsibility" from U.S. intelligence before he left office the following January.

It wasn't until after the Bush administration took power that U.S. intelligence concluded Al Qaeda had sponsored the attack on the ship in the harbor at Aden, Yemen. Some commissioners have been critical of the decision not to launch a retaliatory military strike.

The person, who would speak only on condition of anonymity because Clinton's testimony delved into classified materials, also said the former president explained the rationale for many of the terror-fighting policies that his administration instituted and the message his administration left behind to the incoming Bush administration.

Clinton "did not indicate anything fundamentally that he would have done differently" given what U.S. intelligence knew about Usama bin Laden (search) and the Al Qaeda threat, the person said.

Commission chairman Thomas Kean (search) said Clinton told the commission he has wrestled with the issue of whether his administration could have done more.

"He said he's going back in his mind over and over again about whether there was something more he could've done," Kean told PBS' "NewsHour with Jim Lehrer."

The panel said it didn't plan to release details of the meeting, saying much of it involved classified information.

Commissioners said that Clinton addressed big-picture policy issues.

"He was adamant about trying to work in a bipartisan way to fix the problems," said Democratic commissioner Timothy Roemer, a former U.S. representative from Indiana. "He was quite honest and frank."

John Lehman, a former Navy secretary under President Reagan, agreed.

"He did very well," Lehman told CNN. "He gave us a lot of very helpful insights into things that happened, policy approaches."

A spokesman for Clinton, Jim Kennedy, said the former president was pleased to talk to the commission "and believed it was a very constructive meeting."

Clinton and former Vice President Al Gore consented in February to separate private interviews; Gore is scheduled to meet the panel soon.

President Bush and Vice President Dick Cheney (search) also will meet privately with the full panel in a joint session in coming weeks. They initially restricted the interview to one hour with two panel members, but under mounting public pressure agreed last week to a joint session without time constraints.