Osama bin Laden, the man intelligence officials say is the prime suspect behind Tuesday's hijacking attacks, is the head of a shadowy organization that is believed to have been targeting the United States and its allies since the early 1990s.

Bin Laden, an Islamic fundamentalist and the son of a Saudi billionaire, has been on the FBI's Ten Most Wanted Fugitive list since 1999, and the U.S. State Department has offered a $5 million reward for his arrest.

U.S. prosecutors say bin Laden is the leader of al Qaeda (Arabic for "the Base"), a worldwide network blamed for both successful and failed strikes on U.S. targets. These include the millennium bombing plot, last year's attack on the USS Cole in Yemen and the nearly simultaneous bombings of the U.S. embassies in Tanzania and Kenya.

Bin Laden's anger with the United States stems from the 1990 decision by Saudi Arabia to allow the U.S. to stage attacks on Iraqi forces in Kuwait and Iraq. After the U.S. victory, the U.S. military presence became permanent.

In a CNN interview with bin Laden in 1997, he said the ongoing U.S. military presence in Saudi Arabia is an "occupation of the land of the holy places."

He left Saudi Arabia in 1991 after feuding with the Saudi monarchy, taking an inheritance worth an estimated $250 million with him.

In 1996, bin Laden issued a "fatwah," a religious ruling urging Muslims to kill U.S. troops in Saudi Arabia and Somalia. A second fatwah in 1998 called for attacks on American civilians.

Network dates back to Afghanistan war

Bin Laden began forming his network in 1979, when he went to Afghanistan to fight the Soviets alongside Afghan resistance fighters known as the mujahedeen.

He used his family's connections and wealth to raise money for the Afghan resistance and provide the mujahedeen with logistical and humanitarian aid, and participated in several battles in the Afghan war.

As the war with the Soviets drew to a close, bin Laden formed al Qaeda, an organization of ex-mujahedeen and other supporters channeling fighters and funds to the Afghan resistance.

Once the Soviets pulled out of Afghanistan, bin Laden returned to Saudi Arabia to work for the family construction firm, the Bin Laden Group. He became involved in Saudi groups opposed to the reigning Saudi monarchy, the Fahd family.

In 1994, the Saudi government stripped him of his citizenship and froze his assets in the country.

Al Qaeda linked to other radical groups

Bin Laden is believed to be at the center of an international coalition of Islamic radicals. Al Qaeda has forged alliances with like-minded fundamentalist groups such as Egypt's Al Jihad, Iran's Hezbollah, Sudan's National Islamic Front, and jihad groups in Yemen, Saudi Arabia, and Somalia, according to the U.S. government. Bin Laden's organization also has ties to the "Islamic Group," led at one time by Sheik Omar Abdel Rahman, the Egyptian cleric serving a life sentence since his 1995 conviction for a thwarted plot to blow up various New York landmarks. Two of Sheik Rahman's sons joined forces with bin Laden in the late 1990s.

The U.S. alleges that from 1992 on, bin Laden and other al Qaeda members targeted U.S. military forces in Saudi Arabia and in Yemen and those stationed in the Horn of Africa, including Somalia.

In October 1993, 18 U.S. servicemen involved in the U.S. humanitarian relief effort in Somalia were killed during an operation in Mogadishu. Their bodies were dragged through the streets.

Bin Laden was indicted in 1996 on charges of training the people involved in the attack and in a 1997 interview with CNN, bin Laden said his followers, together with local Muslims, killed those troops.

U.S. law enforcement also alleges that bin Laden has ties to failed attacks on two hotels in Yemen where U.S. troops stayed en route to Somalia.

On August 7, 1998, eight years after the U.S. deployment in Saudi Arabia, a pair of truck bombs exploded outside the U.S. embassies in Nairobi, Kenya and Dar es Salaam, Tanzania.

Bin Laden has denied responsibility, but prosecutors allege his culpability is evident on faxes sent by his London cell to at least three international media outlets. They also point to incriminating statements by certain alleged embassy bombers who are admitted al Qaeda members.

Fourteen days later, on August 20, 1998, President Bill Clinton ordered cruise missile attacks against suspected terrorist training camps in Afghanistan and a pharmaceutical plant in Khartoum, Sudan.

Bin Laden survived the strikes and was indicted by the U.S. on charges of masterminding the attacks in November, 1998.

Four of his alleged supporters were convicted of the bombings on May 29, 2001, and sentenced to life in prison. Several suspects are in custody awaiting trial.

The man who pleaded guilty to a failed plot to bomb Los Angeles International Airport during the millennium celebrations leading up to New Years Day 2000 claimed he was trained at a camp in Afghanistan run by bin Laden.

Ahmed Ressam said he learned how to handle handguns, machine guns, and rocket-propelled grenade launchers and how to assemble bombs made from the explosives TNT and C4.

Bin Laden is suspected to be living in Afghanistan as a guest of its ruling Taliban government.