The Sept. 11, 2001, attacks were supposed to cause twice as much destruction as they did and involved using 10 planes for suicide hijackings, Sept. 11 mastermind Khalid Shaikh Mohammed (search) told U.S. investigators.
Mohammed said that when he first began plotting the attacks with terrorist leader Usama bin Laden (search) in 1996, the original scheme involved the hijacking of five commercial airliners on each U.S. coast, 10 planes in total.
After examining interrogation reports, The Associated Press learned that Mohammed said the that, in its final stages, the hijacking plan called for as many as 22 terrorists and four planes in a first wave. A second wave of suicide hijackings was to follow that were to be aided possibly by Al Qaeda allies in southeast Asia, U.S. officials confirmed to Fox News.
The interrogation reports make clear that Mohammed and Al Qaeda were still actively looking to strike U.S., Western and Israeli targets across the world as of this year.
Mohammed was captured in a March 1 raid by Pakistani forces and CIA operatives (search) in Rawalpindi. He is being interrogated by the CIA at an undisclosed location.
Mohammed's interrogations have revealed the planning and training of operatives was extraordinarily meticulous, including how to blend into American society, read telephone yellow pages, and research airline schedules.
Over time, bin Laden scrapped various parts of the Sept. 11 plan, including attacks on both coasts and hijacking or bombing some planes in East Asia, Mohammed said that shed new light on the origins and evolution of the plot of Sept. 11, 2001.
Addressing one of the questions raised by congressional investigators in their Sept. 11 review, Mohammed said he never heard of a Saudi man named Omar al-Bayoumi who provided some rent money and assistance to two hijackers when they arrived in California.
Congressional investigators have suggested Bayoumi could have aided the hijackers or been a Saudi intelligence agent, charges the Saudi government vehemently deny. The FBI has also cast doubt on the theory.
How Much He Aided the Hijackers
Mohammed claims he did not arrange for anyone on U.S. soil to assist hijackers Khalid al-Mihdhar and Nawaf al-Hazmi. He said there "were no Al Qaeda operatives or facilitators in the United States to help al-Mihdhar or al-Hazmi settle in the United States," one of the reports state.
Al-Mihdhar and al-Hazmi were on the plane that was flown into the Pentagon.
Mohammed portrays those two hijackers as central to the plot, and even more important than Mohammed Atta, initially thought to be the ringleader. Mohammed said he communicated with al-Hazmi and al-Mihdhar while they were in the United States by using Internet chat software.
Mohammed said al-Hazmi and al-Mihdhar were among the four original operatives bin Laden assigned to him for the plot; those were the only two hijackers whom U.S. authorities were frantically seeking for terrorist ties in the final days before Sept. 11.
Terrorism experts say the facts emerging from the interrogation report are quite revealing and give a clearer picture of how Al Qaeda operates.
"This news coming out that the plot was shrunk down is probably from an operational standpoint, they were afraid of the word getting out, leaking out," said Fox News military analyst Ret. Navy Capt. Chuck Nash. "The more people you have involved, the more chance you have of being discovered."
Officials believe Mohammed knows the locations of many of the remaining Al Qaeda leaders. They also say he was active in Al Qaeda's attempts to acquire chemical and biological weapons.
Peter Brookes, a former CIA special operations officer and now a fellow for national security affairs at The Heritage Foundation, cautioned that Mohammed's information may now be stale so far as it helps current terrorism investigations.
"The downside is this is all six months old now. They're [ Al Qaeda's] trade craft is changing significantly," Brookes told Fox News on Monday. "We need to be very careful in looking toward the future seeing how A Qaeda and other groups are changing their tactics."
Brookes noted that Al Qaeda may be looking to recruit people who wouldn't fit the traditional description of a terrorism -- looking, for example, for recruits from a variety of ethnic groups and countries that aren't known to be anti-American.
"Al Qaeda is changing their tactics so that they can continue to be as lethal as they have bee in the past," Brookes said.
U.S. authorities continue to investigate the many statements Mohammed made. They have been able to corroborate with other captives and evidence much of his account.
Recruiting the Hijackers
Mohammed said the hijacking teams were originally made up of members from different countries where Al Qaeda had recruited, but that later bin Laden chose to use a large group of young Saudi men.
Mohammed learned "there was a large group of Saudi operatives that would be available to participate as the muscle in the plot to hijack planes in the United States."
Saudi Arabia was bin Laden's home, though it revoked his citizenship in the 1990s. Saudis have suggested that bin Laden has been trying to drive a wedge between the United States and their kingdom.
U.S. intelligence has suggested that Saudis were chosen because there were large numbers willing to follow bin Laden and they could more easily get into the United States because of the countries' friendly relations.
Mohammed said some of the original operatives has trouble getting into the United States.
He described other terror plots that were being planned or had been temporarily disrupted when he was captured, including one planned for Singapore.
Mohammed said he had worked in 1994 and 1995 in the Philippines with Ramzi Yousef, Abdul Hakim Murad and Wali Khan Amin Shah on the foiled Bojinka plot to blow up 12 Western airliners simultaneously in Asia.
After Yousef and Murad were captured, Mohammed began to devise a new plot that focused on hijackings on U.S. soil.
In 1996, he went to meet bin Laden to persuade the Al Qaeda leader "to give him money and operatives so he could hijack 10 planes in the United States and fly them into targets," one of the interrogation reports state.
Mohammed wanted to pick five targets on each coast, but bin Laden didn’t think that was practical.
Mohammed said bin Laden offered him four operatives -- al-Mihdhar and al-Hazmi as well as two Yemenis, Walid Muhammed bin Attash and Abu Bara al-Yemeni.
"All four operatives only knew that they had volunteered for a martyrdom operation involving planes," one report stated.
The first major change to the plans occurred in 1999 when the two Yemeni operatives could not get U.S. visas. Bin Laden offered additional operatives, including a member of his personal security detail. The original two Yemenis were instructed to focus on hijacking planes in East Asia.
Mohammed considered using a scaled-down version of the Bojinka plan that would have bombed commercial airliners, and that he even considered using shoe bombs.
The plot, he said, eventually evolved into hijacking a small number of planes in the United States and East Asia and either having them explode or crash into targets simultaneously.
By 1999, the four original operatives picked for the plot traveled to Afghanistan to train at one of bin Laden's camps. The focus was on specialized commando training, not piloting jets.
The Plot Thickens
A key event in the plot, Mohammed said, was a meeting in Kuala Lumpur, Malaysia, in January 2000, that included al-Mihdhar, al-Hazmi and other Al Qaeda operatives. The CIA had the meeting monitored by Malaysian security, but it did not realize the significance of the two eventual hijackers until just before the attacks.
In spring 2000, bin Laden canceled the idea for hijackings in East Asia because he thought "it would be too difficult to synchronize" attacks in the United States and Asia.
Mohammed reached out to an Al Qaeda linked group in southeast Asia, Jemaah Islamiyah. He began "recruiting JI operatives for inclusion in the hijacking plot as part of his second wave of hijacking attacks to occur after Sept. 11," one report summary said.
An operative of Jemaah Islamiyah's operations chief, Riduan Isamuddin Hambali, later began training possible recruits for the second wave of attacks.
One of those who received training in Malaysia before coming to the United States was Zacarias Moussaoui, the Frenchman accused of conspiring with the Sept. 11 attacks. Moussaoui has denied being part of the Sept. 11 plot, and U.S. and foreign intelligence officials have said he could have been set for hijacking a plane in later attacks.
Fox News' Kelly Wright and The Associated Press contributed to this report.