But Lehman contended that the nation needed to get to the cause of terrorism.
"We've really gotten rid of most, if not all, of the theatre commanders of al Qaeda, but we have not yet, as a nation, addressed the root cause," Lehman said. "The root cause is this jihadist ideology."
Commissioner Richard Ben-Veniste, a Democratic attorney who headed both the Watergate Task Force in the Watergate Special Prosecutor's Office and later the minority side of the Senate Whitewater Committee, agreed that America must confront the ideology fueling al Qaeda.
"There are far more terrorists now than there were on 9/11," Ben-Veniste said. "That's why we have not killed or captured Osama bin Laden five years after 9/11, and he remains the central focus spiritually, ideologically [of al Qaeda]."
Ben-Veniste cited the Iraq war as a distraction to the war on terror.
But Kean said the war in Iraq is creating radicals.
"Where we are right now is in a very difficult place. There's no question the war in Iraq is radicalizing the people in that area," Kean said. "That's where terrorists like to breed."
Gorelick said the situation in Afghanistan, due in part to Iraq, is spiraling out of control.
"If you have a place that is chaotic … it's going to be a breeding ground and a safe haven for folks like the leaders of al Qaeda," she said.
Turning back to Iraq, Gorelick said, "We may not have liked Saddam Hussein but we didn't have a haven for terrorists and now we do."
Looking toward the future, all of the commissioners agreed that more could and should be done.
"We are in a generational war with Islamic radicals," Ben-Veniste said.
Lehman pushed for a greater investment in global education.
"We have to rebuild a coalition," Lehman said.
But he stressed that the United States must "address the issue of all these jihadist schools."
George Stephanopoulos' entire interview with four members of the 9/11 Commission can be viewed at "This Week's" Web page at www.abcnews.com.