The panel recommended many reforms, including several that Bush can implement without the permission of Congress. One is to ensure that John Negroponte -- whom Bush has nominated to be his director of national intelligence -- has the authority to unilaterally settle any disputes between intelligence agencies.
In releasing the report, Bush said he accepted its conclusions.
"The commission presented me with their recommendations, which are thoughtful and extremely significant," Bush said. "The central conclusion is one that I share -- America's intelligence community needs fundamental change to enable us to successfully confront the threats of the 21st century."
The president then left the co-chairmen of the commission to answer reporters' questions. They are retired judge Laurence Silberman, a member of Bush's Republican Party, and former Senator Charles Robb of the opposition Democratic Party.
The first question was how U.S. intelligence could have been so wrong in concluding that now-deposed Iraqi President Saddam Hussein had a significant arsenal of biological and chemical weapons, and had a robust program to develop nuclear weapons.
This was a key argument used by Bush and Vice President Dick Cheney in the months preceding the invasion of Iraq two years ago.
Essentially, Silberman replied, American intelligence agents drew this conclusion based on old assumptions from the Gulf War of 1991 and a dearth of new data since then.
"The intelligence community operated on presumptions, or assumptions, based on what they had seen in 1991, and they continued on with those presumptions," Silberman said.
Silberman added that what little they did get they made fit into these presumptions based on Saddam's previous behavior.
At the same time, Silberman said, American intelligence officials were "resistant" to the idea that Saddam had a significant connection to Al-Qaeda, which is blamed for the 11 September 2001 attacks in the United States.
The co-chairmen also were asked whether agents may have made their reports suit what they perceived the administration wanted to hear. Robb said there is no evidence of that.
"We examined every single instance that had been referred to in print or otherwise, to see if there was any occasion where a member of the administration or anyone else had asked an analyst or anybody else associated with the intelligence community to change a position that they were taking or whether they felt there was any undue influence," Robb said. "And we found absolutely no instance."
The report did not stop at making recommendations and outlining past problems. It said the weaknesses in U.S. intelligence- gathering remain, to the point where Americans know very little about current weapons threats, particularly nuclear threats.
Silberman and Robb were repeatedly asked about the current problems, particularly as they relate to efforts to persuade North Korea and Iran to abandon their nuclear ambitions. The two men said that information is classified.