Was Kuwaiti Behind 9/11 Attacks?

He's described as a little overweight, and may still wear a beard, but Kuwaiti-born Khalid Shaikh Mohammed is the man some investigators believe who first came up with the idea of flying jet liners into the World Trade towers and the Pentagon last September.

CBS News Correspondent Jim Stewart reports that according to a top U.S. counterterrorism official, Mohammed is a lieutenant of Osama bin Laden who had previously plotted to attack the World Trade Center and to bomb several airliners simultaneously.

Other bin Laden lieutenants are also believed to have helped put together the Sept. 11 attacks, but evidence is mounting that Mohammed was at the center of the operational planning.

A second U.S. official, also speaking on condition of anonymity, acknowledged that Mohammed played a critical role in planning the attacks but said questions remain about the extent of his leadership.

The official said other bin Laden lieutenants, including Abu Zubaydah, now in U.S. custody, are also believed to have played top organizational roles.

According to Zubaydah, who fingered Mohammed as the mastermind behind the Sept. 11 attacks, Mohammed is al Qaeda's top surviving talent scout and had handpicked men from terrorist training camps in Afghanistan for missions overseas.

U.S. officials told CBS News they now have evidence Mohammed met with some of the 9/11 hijackers at their Hamburg, Germany apartment in 1999.

That is viewed as a major development by some investigators because Mohammed is accused of working with Ramzi Yousef in the first bombing of the World Trade Center, which left six dead in 1993. He and Yousef also were accused of plotting in 1995 to bomb several trans-Pacific airliners heading for the United States. Yousef, now serving a life sentence in the United States after being convicted in the 1993 World Trade Center bombing, also is believed to have planned to crash a plane into CIA headquarters.

Analysts say its now becoming clearer that all the attacks can be traced to al Qaeda.

One of the FBI's most-wanted terrorists, Mohammed is at large in Afghanistan or nearby, the law enforcement official told The Associated Press on Tuesday.

Mohammed was charged by federal prosecutors in New York in 1996 in connection with the alleged 1995 plot. The State Department is offering a reward of up to $25 million for information leading to his capture.

Mohammed, 36, is one of the highest-ranking al Qaeda leaders still at large, officials said, and continues to plan attacks against U.S. interests. Although he was born in Kuwait, officials there say he is a Pakistani national and note that people born in Kuwait do not automatically qualify for citizenship.

According to the counterterrorism official, within three months of Sept. 11, the FBI learned that Mohammed had performed some financial transactions to fund the attacks; since then the United States has gathered other significant evidence pointing to him as the key planner. The official declined to go into detail, citing a need to protect intelligence information.

Other officials said Abu Zubaydah has provided details on Mohammed, whose aliases include Ashraf Refaat Nabith Henin, Khalid Abdul Wadood, Salem Ali and Fahd Bin Abdallah Bin Khalid.

U.S. officials have repeatedly said that capturing or killing bin Laden's cadre of lieutenants — men like Mohammed — is a key goal in the war on terrorism. In some ways, they are considered as dangerous as bin Laden: Where al Qaeda's leader serves as an inspiration to his followers, his top aides conduct the nuts-and-bolts planning of attacks.

The lieutenants are said to pick targets and attack dates, maintain operational secrecy and provide money and training to the foot soldiers and overseas cells chosen to carry them out — sometimes at the cost of their own lives.

Most of the 19 suicide hijackers are thought not to have known the entirety of the Sept. 11 plot — or that they were going to die but Mohammed apparently did, the counterterrorism official said.

Mohammed has not been charged in connection with the attacks, in which hijacked airliners crashed into the World Trade Center, the Pentagon and a southwestern Pennsylvania field, killing more than 3,000.

Some of the hijackers trained at Abu Zubaydah's Khalden camp in Afghanistan, officials said. Generally, though, the hijackers trained in groups of one or two at several camps, and they were kept apart from most other trainees.

Abu Zubaydah, captured in Pakistan in March, is said to have told U.S. interrogators that the hijacked plane that crashed in Pennsylvania was destined for the White House, suggesting he knew of the planning.

According to investigators, the Sept. 11 attacks were largely paid for by Shaikh Saiid al-Sharif, also known as Mustafa Ahmed al-Hisawi, who is bin Laden's financial chief. Officials traced a number of financial transactions between him and several of hijackers, but Shaikh Saiid was not believed to have the wherewithal to plan an operation of Sept. 11's magnitude. He is at large.

A fourth bin Laden lieutenant, Tawfiq Attash Khallad, is also suspected of playing a planning role. He met with Sept. 11 hijackers Khalid Almihdhar and Nawaf Alhazmi in Kuala Lumpur, Malaysia, in January 2000, just before Almihdhar and Alhazmi entered the United States. Khallad paid for some of the pair's travel before Sept. 11, the counterterrorism official said.

Khallad, believed to be a chief planner of the October 2000 USS Cole bombing, remains at large, the official said.

Some key connections have yet to be worked out, the official acknowledged, such as who selected the hijackers to conduct the Sept. 11 operation.

Bin Laden and his top two deputies, Ayman al-Zawahri and Mohammed Atef, were believed to have known about the attacks in advance, by virtue of their station in al Qaeda. Al-Zawahri's family was killed by a U.S. airstrike in Afghanistan. It is not known where he is.

Atef, killed by U.S. airstrikes in November, had a martyrdom video of other purposed hijackers at his house. Ramzi Binalshibh was a member of Atta's cell in Germany, but was unable to enter the United States. He remains at large.

Bin Laden himself admitted foreknowledge of the Sept. 11 attacks on a Nov. 9 videotape of him having dinner with a Saudi sheik, al-Zawahri and some other supporters.