WASHINGTON (AP) _ Osama bin Laden has survived despite spending much of his life opposing the great powers of the world.
And while bin Laden, the West's chief suspect for Tuesday's slaughter, likely remains confined to a network of camps and caves in eastern Afghanistan, tracking him consistently has proved extraordinarily difficult for U.S. intelligence agencies.
America is undeterred, President Bush said Saturday. ``If he thinks he can hide and run from the United States and our allies he will be sorely mistaken.'' Bush, for the first time, identified bin Laden as a suspect in the attacks. ``Those who make war against the United States have chosen their own destruction,'' the president said.
Last December, the Clinton administration prepared to strike bin Laden when officials believed they had solid information of his whereabouts. After an internal debate, they pulled back in part over concerns that the information was out of date _ further driving home that realtime intelligence on the man is hard to come by.
It isn't for lack of trying. The full assets of the intelligence community _ from CIA spies, to National Security Agency wire and computer taps, to the military's satellites _ are used to track bin Laden's activities. The United States and its allies also share information.
Intelligence officials, however, avoid discussing how successful those efforts are for fear of giving away U.S. capabilities.
It's clear bin Laden knows U.S. spy methods and takes steps to avoid them. He moves fast and goes into hiding. He stops using communications channels he learns are monitored such as his satellite phone.
``The fact that we seem to have so little information about his recent activities suggests that they've made some important innovation in communications and is something we're going to have get up to speed on fast,'' said Daniel Benjamin, a former National Security Council staffer and terrorism expert now with the Center for Strategic & International Studies. ``It is quite possible that they're doing most of their communications by face-to-face conversation.''
That calls for human intelligence _ U.S. agents able to observe those conversations directly. So far, finding those has proved almost impossible for the CIA. Just as the United States does with its most serious secrets, bin Laden keeps sensitive information close, sharing it with few people.
Despite his efforts, the CIA, working with its foreign counterparts, has managed some victories, thwarting attacks by bin Laden's network in Jordan, Egypt, Kenya and the Balkans in recent years.
Among other countries, Pakistan is believed to have the best intelligence on the Islamic militants operating in eastern Afghanistan. Pakistani intelligence sources said bin Laden changed locations immediately after the attacks on New York' World Trade Center and the Pentagon.
So far, investigators have tied the attacks to known associates of bin Laden and his organization, Al-Qaeda, or ``The Base.''
A telephone call, tapped by U.S. intelligence officers, between two of those associates was an early clue. More links have accumulated since, said a U.S. official, speaking on condition of anonymity.
As they learn the names of those involved in the attacks, investigators can check them against a huge matrix of suspected terrorists maintained by intelligence agencies.
Bin Laden dropped out of sight in August 1998, when the United States fired cruise missiles into his eastern Afghanistan camps in retaliation for the bombings of two U.S. embassies in East Africa.
Now in his mid-40s, he was last seen in public in February, at his son's wedding in the southern Afghan city of Kandahar.
A scion of a wealthy Saudi Arabian family, bin Laden bankrolled opposition to the invading Soviet Union, which ultimately abandoned its occupation in 1989. In 1996, he publicly declared war on the United States and has been tied to numerous acts of terrorism since.