When the horrifying news spread around the globe Tuesday that the twin towers of New York's World Trade Center were reduced to rubble and the Pentagon had been attacked by hijacked American passenger jets used as missiles, it took very little for the name of Osama bin Laden to emerge as the suspected mastermind.

Bin Laden, the Saudi-born businessman believed to be holed up at a secret location in Afghanistan, tops the FBI's Most Wanted fugitive list and was implicated in the 1993 bombing of the World Trade Center, the 1998 attacks on two U.S. embassies in Africa and other acts of terror. In 1997, bin Laden declared that the Islamic fundamentalists he leads would wage a "jihad," or holy war, against the U.S. and Saudia Arabia.

An Arab journalist with access to bin Laden told the Associated Press that bin Laden had warned of a "very big one" being planned by Islamic fundamentalists he leads. Abdel-Bari Atwan, editor of the London-based al-Quds al-Arabi news magazine, said bin Laden was almost certainly behind the attacks, the full extent of which may not be know for days and weeks as authorities count the bodies.

No one has claimed responsibility for Tuesday's attacks, and the Afghan government which plays host to bin Laden rejected speculation he was involved. One expert cautioned against assuming bin Laden could pull off such a complex operation.

But other experts said the millionaire Saudi exile was the most likely suspect.

"I can think of only one person who could pull this off" -- bin Laden, said Harvey Kushner, a terrorism expert at Long Island University in New York.

"When you think of the coordination this took, it's historic. When you think of the measures that will have to be put into place to ratchet up security in the United States, it's monumental," Kushner said in New York. "This opens up a new era in the history of terrorism."

While many Americans know his name, few know much more about the accused terrorist who has vowed to target America.

The following Q&A about Bin Laden was compiled from Internet sources, including government and terrorism-related Web sites:

Q. Who is Osama bin Laden?

A. Osama bin Laden, whose name is sometimes cited as Usama bin Ladin, was born around 1955 in Saudi Arabia. His wealthy father owned a construction company that held a lot of government contracts. In 1979, bin Laden left Saudia Arabia to join the Afghan Arabs who successfully fought off the Soviet invasion of Afghanistan, according to an unclassified CIA factsheet. (The Smoking Gun)

Q. Why do many suspect bin Laden masterminded the New York and Washington terrorist acts?

A. Bin Laden's name surfaced in connection with acts of terror around the world, including the attacks in Saudia Arabia in November 1995 and Dhahran the following June that left 30 people dead, including 24 Americans. He is also implicated in the assassination attempt on Egyptian president Mubarak in Ethiopia in 1995; the World Trade Center bombing in 1993 that killed three and injured hundreds; and the Somali attack on American forces that left hundreds wounded. (Associated Press)

Q. What does bin Laden have against the U.S.?

A. In his own words, bin Laden told ABC News in 1998 that the soldiers in his "fatwa" against the U.S. are trying to protect Muslims safe from America's interference in Middle East affairs. "Allah ordered us in this religion to purify Muslim land of all non-believers, and especially the Arabian Peninsula where the Ke’ba is. After WWII, the Americans became more aggressive and oppressive, especially in the Muslim world," bin Laden said. " ... We must use such punishment to keep your evil away from Muslims, Muslim children and women. American history does not distinguish between civilians and military, and not even women and children. They are the ones who used the bombs against Nagasaki. Can these bombs distinguish between infants and military?" (ABC News.com)

Q What is a fatwa?

A. A fatwa is a religious edict. In 1998, bin Laden issued a fatwa declaring it acceptable to kill Americans, civilians included, according to the CIA. "To kill Americans and their allies, both civil and military, is an individual duty of every Muslim who is able, in any country where this is possible." (CIA)

Q. What are U.S. officials doing to bring down bin Laden's terrorist network?

A. In 1998, bin Laden was indicted in New York on federal charges stemming from the bombings of the U.S. embassies in Kenya and Tanzania. There is a $5 million reward for information leading to his arrest anywhere in the world. He remains at the top of the list of the FBI's Most Wanted fugitives.

Q. Why has bin Laden been outside the long reach of the U.S. intelligence community?

A. Bin Laden has been protected in recent years by the Taliban, the ruling Muslim regime in Afghanistan. Although the Taliban expressed sympathy for the attacks on U.S. soil quickly and have generally denounced terrorism, its leaders have stopped short of calling bin Laden a terrorist. As recently as July, the Taliban praised bin Laden for his services to Afghanistan and vowed never to betray a "friend" because of the United States' pressure. (CNN.com)

Q. Why doesn't the U.S. just take bin Laden out with a missile?

A. President Clinton tried that in 1998 in response to the embassy bombings. American cruise missiles pounded sites in Afghanistan and Sudan. Bin Laden escaped injury.

Q. Could the prime suspect be the wrong suspect?

A. Bin Laden has yet to claim any responsibility for the worst act of terrorism ever on U.S. soil and remains, under the American system of justice, innocent until proven guilty. Whoever coordinated the hijacking and crashing of four American airliners simultaneously, most experts agree today, gave much time and thought to the effort. Finally, it should be noted that initial suspicion focused on foreign religious extremist groups when the federal building was blown up in 1995. This summer, Timothy McVeigh, an American angry at his own government for the deaths of Branch Davidians at Waco, was executed for that terrorist act.

Q: Is there any other reason why bin Laden, if he is behind the attack, might have acted now?

A: Two of the four men convicted of bombing two United States embassies in Africa in 1998 were scheduled to be sentenced next Wednesday. The terrorists, Lebanese-American Wadih el-Hage and Jordanian Mohamed Saddiq Odeh, were convicted of conspiracy and expected to receive life sentences for their roles in the embassy bombings.

The Associated Press contributed to this report.