The 31 on his list range from the stunningly vicious suicide hijackings of Sept. 11, 2001, to others that current and former government officials say were more talk than concrete plans, such as a plot to kill Jimmy Carter and other former U.S. presidents.

The officials spoke on condition of anonymity, noting Mohammed's activities are likely to be the subject of an upcoming military tribunal.

His confession, his first public statement since his March 2003 capture in Pakistan, came in a closed-door hearing in the newly established U.S. tribunal process. A 26-page transcript of the Saturday session at Guantanamo Bay, Cuba, was made public Wednesday night.

While there apparently is truth in much of the statement, several officials said, there's also an element of self-promotion. They view the claims as at least in part a rallying cry to bolster his image and that of al-Qaida in the only venue Mohammed has left: a military courtroom from which the public is barred.

"I have never known a criminal- either terrorist or otherwise - that didn't exaggerate," said Michigan Rep. Mike Rogers, a former FBI agent and the top Republican on the terrorism panel of the House Intelligence Committee.

Pentagon spokesman Bryan Whitman said authorities would decide the credibility of Mohammed's claims if he is tried. "These are his words," Whitman said.

The United States linked Mohammed closely to the attacks of 9/11, and his statement said he was responsible "from A to Z." Officials don't doubt his claim that he beheaded Wall Street Journal reporter Daniel Pearl with what he called his "blessed right hand." And he corroborates al-Qaida's known interest in attacking embassies, London's Heathrow Airport, the New York Stock Exchange and other targets.

But his role in some plots may be more minor than his hands-on involvement in coordinating the attacks of 9/11 - evidence of which was found on his computer when he was captured. Some of the plots were formulated in al-Qaida's early years, when alliances among jihadists were even more fluid than they are today.

"If you look at him having a senior position in al-Qaida, when he says he's responsible, it can be interpreted in a lot of different ways," said Ben Venzke, head of the Virginia-based IntelCenter, a government contractor that monitors al-Qaida messaging.

Some examples:

Mohammed claims that he was "responsible for the 1993 World Trade Center Operation," which killed six and injured more than 1,000 when a bomb was detonated in an underground garage. Six jihadists with ties to international terror networks are serving life sentences. One official said Mohammed didn't hatch the plot, but he and elements of al-Qaida may have supported it.

He also claims to be responsible for the bombing of a nightclub in Bali, Indonesia, which was frequented by British and Australian tourists. Current and former officials say that his role was probably that of a financier for an al-Qaida affiliate group ¡ª Jemaah Islamiyah ¡ª operating in Southeast Asia.

Mohammed's link "could have been as small as arranging a safe house for travel. It could have been arranging finance," Rogers said. "But for his own self-worth, he may have tended to say, 'I was responsible for Bali.'"

He claims to have been responsible for providing financial support to "hit American, Jewish and British targets in Turkey." That's probably a reference to the 2003 bombing of two synagogues, a British-based bank and the British consulate in Istanbul, killing 58 people including the British consul-general.

Prosecutors said Osama bin Laden personally ordered the plot, and Mohammed was not named as a key provider of financial support during a three-year trial. Instead, Turkish authorities say a Syrian ¡ª Loa'i Mohammad Haj Bakr al-Saqa ¡ª masterminded the attacks and ran $170,000 between al-Qaida and the Turkey-based militants.

And Mohammed claimed he shared responsibility ¡ª he stressed shared ¡ª for an attempt to assassinate Pope John Paul II during a 2005 stop in the Philippines. Authorities later blamed the plot on Ramzi Yousef, who was convicted of masterminding the 1993 World Trade Center bombing and accused of plotting to blow up U.S. airliners. Yousef was never charged in plotting to kill the pope.

Mohammed's claims help answer some questions. Some intelligence officials have long believed that would-be shoe bomber Richard Reid was part of a larger plan to take down airliners after 9/11, in part, because of e-mails he wrote that were discovered on a computer in a Paris Internet cafe.

Another British citizen has been convicted in the plot. In his statement Saturday, Mohammed said he was responsible for the shoe bomber operation "to down two American airplanes."

Current and former government officials say the CIA spent hundreds ¡ª if not thousands ¡ª of hours interrogating Mohammed and would have heard him describe in great detail precisely what he claims to have done in each plot. The transcript provided a snippet of his claims, officials said.

A CIA official declined to analyze Mohammed's statements.

One official cautioned that many of Mohammed's claims during interrogation were "white noise"- designed to send the U.S. on wild goose chases or to get him through the day's interrogation session.

In the Defense Department transcript, Mohammed said his statement was not made under duress. But Mohammed and human rights advocates have alleged that he was tortured, and legal experts say that could taint all his statements.

"In light of the rambling nature of his statements, and the views of some that he is prone to exaggerate his importance, we cannot feel confident we know exactly the level of his involvement in various prior attacks," said Joshua Dressler, a criminal law expert at Moritz College of Law at Ohio State University.

The CIA has denied it uses torture. "The agency's terrorist interrogation program has been conducted lawfully, with great care and close review, producing vital information that has helped disrupt plots and save lives," spokesman Paul Gimigliano said.