"I decapitated with my blessed right hand the head of the American Jew, Daniel Pearl, in the city of Karachi, Pakistan," Mohammed is quoted as saying in a transcript of a military hearing at Guantanamo Bay, Cuba, released by the Defense Department.
"For those who would like to confirm, there are pictures of me on the Internet holding his head," he added.
Mohammed's claimed involvement in the 2002 slaying of the Wall Street Journal reporter was among 31 attacks and plots — some of which never came to fruition — he took responsibility for in a hearing Saturday at the U.S. naval prison at Guantanamo Bay, Cuba, the Pentagon said.
It released the bulk of the transcript late Wednesday, but held back the section about Pearl's killing to allow time for his family to be notified, said Defense Department spokesman Bryan Whitman.
Sealing a legacy of historical notoriety, Mohammed portrayed himself as al Qaeda's most ambitious operational planner in a confession to a U.S. military tribunal.
The Guantanamo Bay hearing, known as a Combatant Status Review Tribunal, is a formality allowing the military to certify a detainee as an "enemy combatant" who warrants further detention and can be prosecuted by a military tribunal. In Mohammed's case,"For sure, I'm American enemies," he said. "I don't have anything to say that I'm not enemy," reports CBS Evening News producer Phil Hirshkorn.
Mohammed's language offers what CBS news consultant Paul Kurtz says is a fascinating insight into the mastermind behind Sept. 11.
"He is a warrior, and he's taking on his enemy the way he sees fit," Kurtz tells CBS News national security correspondent David Martin. "He's sorry about losing 3,000 people over the World Trade Center attacks. Nonetheless, this is the language of war. He says that several times in the transcript."
Many plots, including a previously undisclosed plan to kill several former U.S. presidents, were never carried out or were foiled by international counterterrorism authorities.
"I was responsible for the 9/11 operation from A to Z," Mohammed said in a statement read Saturday during a Combatant Status Review Tribunal at the U.S. detention facility at Guantanamo Bay, Cuba. Mohammed's confession was read by a member of the U.S. military who is serving as his personal representative.
The Pentagon had released a 26-page transcript of the closed-door proceedings on Wednesday night. Some material was omitted, and it was not possible to immediately verify details. The document refers to locations for which the United States and other nations have issued terrorism warnings based on what they deemed credible threats from 1993 to the present.
President Bush announced that Mohammed and 13 other alleged terror operatives had been moved from secret CIA prisons to the U.S. Naval Base at Guantanamo Bay last year. They are considered the 14 most significant captures since 9/11.
The military began the hearings last Friday to determine whether the 14 should be declared "enemy combatants" who can be held indefinitely and prosecuted by military tribunals.
Whitman said authorities would decide how credible it is that Mohammed participated in so many plots if he is tried by a military tribunal, which many expect will eventually happen.
"These are his words." Whitman said.
Mohammed, known as KSM among government officials, was last seen haggard after his capture in March 2003, when he was photographed in a dingy white T-shirt with an over-stretched neck. He disappeared for more than three years into a secret detention system run by the CIA.
In his first public statements since his capture, his radical ideology and self-confidence came through. He expressed regret for taking the lives of children and said Islam does not give a "green light" to killing.
Yet he finds room for exceptions. "The language of the war is victims," he said. He also said that in the same way that some consider George Washington, the first U.S. president, to be a hero for his role in the Revolutionary War, many Muslims view al Qaeda leader Osama bin Laden in the same light. "He is doing same thing. He is just fighting. He needs his independence."
In laying out his role in 31 attacks, his words drew al Qaeda closer to plots of the early 1990s than the group has previously been linked, including the 1993 World Trade Center truck bombing in which six people died.
Six people with links to global terror networks were convicted in federal court and sentenced to life in prison for that attack.
Mohammed made clear that al Qaeda wanted to down a second trans-Atlantic aircraft during would-be shoe bomber Richard Reid's operation.
If the 14 are declared enemy combatants, as expected, the military would then draft and file charges against them. The detainees would be tried under the new military commissions law signed by Mr. Bush in October.
The military barred reporters or other independent observers from the sessions for the 14 operatives and is limiting the information it provides about them, arguing that it wants to prevent the disclosure of sensitive information.
Legal experts have criticized the U.S. decision, and The Associated Press filed a letter of protest, arguing that it would be "an unconstitutional mistake to close the proceedings in their entirety."
The transcripts refer to a claim by Mohammed that he was tortured by the CIA, although he said he was not under duress at Guantanamo when he confessed to his role in the attacks. The CIA has said its interrogation practices are legal, and it does not use torture.
Kenneth Roth, executive director of Human Rights Watch, questioned the legality of the closed-door sessions and whether the confession was actually the result of torture.
"We won't know that unless there is an independent hearing," he said. "We need to know if this purported confession would be enough to convict him at a fair trial or would it have to be suppressed as the fruit of torture?"
In listing the 28 attacks he planned and another three he supported, Mohammed said he tried to kill international leaders including Pope John Paul II, President Clinton and Pakistani President Pervez Musharraf.
He said he planned the 2002 bombing of a Kenya beach resort frequented by Israelis and the failed missile attack on an Israeli passenger jet after it took off from Mombasa, Kenya.
He also said he was responsible for the bombing of a nightclub in Bali, Indonesia. In 2002, 202 were killed when two nightclubs there were bombed.
Other plots he said he was responsible for included planned attacks against the Sears Tower in Chicago, the Empire State Building and New York Stock Exchange in New York City, the Panama Canal, and Big Ben and Heathrow Airport in London — none of which happened.
The Pentagon also released transcripts of the hearings of Abu Faraj al-Libi and Ramzi Binalshibh. Both refused to attended the hearings, although al-Libi submitted a statement claiming that the hearings are unfair and that he will not attend unless it is corrected.
"The detainee is in a lose-lose situation," he said.
Al-Libi, whose name means he is a Libyan, reportedly masterminded two bombings 11 days apart in Pakistan in December 2003 that targeted Musharraf for his support of the U.S.-led war on terror.
Binalshibh, a Yemeni, is suspected of helping Mohammed with the 9/11 attack plan on New York City and Washington and is also linked to a foiled plot to crash aircraft into London's Heathrow Airport. His hearing was conducted in his absence.