Plotters of the assault on the World Trade Center and the Pentagon learned from the mistakes of their terrorist predecessors, reducing the chances of early detection and increasing the deadly effectiveness of their attack, intelligence experts said yesterday.
Unlike earlier conspiracies foiled by an indiscreet comment or an intercepted conversation, the hijackers and their superiors launched Tuesday's coordinated attack with what appeared to be total surprise. Significant players in the intelligence community learned about the assault from television.
U.S. intelligence agencies find themselves defending their abilities in the aftermath of the deadliest terrorist assault in the country's history. Sen. Richard C. Shelby (R-Ala.), vice chairman of the Senate Select Committee on Intelligence, said the incident demonstrates the need for a broader array of recruits familiar with other cultures and languages.
"If we had a warning and missed it, that is a failure of intelligence, big time," Shelby said after being briefed by Attorney General John D. Ashcroft and FBI Director Robert S. Mueller III. "If we didn't have any inkling of this event, as well-planned and well-executed as it became, that's a failure, too."
Sen. Bob Graham (D-Fla.), intelligence committee chairman, said it was "premature" to say whether the failure was a result of the limitations of intelligence gathering or from people not doing their jobs. He suspects authorities did not have sources capable of penetrating the terrorist organization in the United States or abroad. He also said the group likely communicated by computer, taking advantage of "shortfalls" in the ability to intercept electronic traffic.
No group has taken responsibility for Tuesday's carnage. U.S. intelligence sources believe the attack was carried out by terrorists with ties to Osama bin Laden, a wealthy Saudi Arabian who trains and finances an array of Islamic fundamentalists. Early evidence suggests the participation of disciplined warriors operating in small cells -- likely communicating face-to-face and leaving few written records.
"This is the hardest target there is," said Daniel Benjamin, a former National Security Council counterterrorism specialist. "There's going to be an awful lot of witch-hunting in the weeks ahead, but it is fair to say that the intelligence community has been knocking itself out and has known that bin Laden is a major threat."
Bin Laden has been the most important target of U.S. counter-terrorism forces for years, according to CIA sources. Earlier this year, U.S. authorities warned Americans living abroad that bin Laden's network planned attacks on U.S. targets overseas.
There was a time when U.S. agencies monitored bin Laden and his associates by following the signal of his satellite telephone. As with other Middle Eastern terrorist groups, they often boasted about their intentions or their successes. About two years ago, word leaked about the bin Laden intercepts, and his phone went silent.
Not all sources have been shut down, however. After the attacks on Tuesday, intelligence officers listened to a conversation between bin Laden associates who said they had hit two targets in the United States, Sen. Orrin G. Hatch (R-Utah) told reporters.
Certain details of the devastating World Trade Center assault suggest that the perpetrators of Tuesday's terror studied the flaws of 1990s conspiracies, including an attempt to destroy one of the twin towers.
A car bomb that exploded in a World Trade Center basement, killing six people, was designed to topple the 110-story buildings, Ramzi Ahmed Yousef, mastermind of the operation, told a Secret Service agent. Indeed, the operation was intended to include attacks on the United Nations headquarters, the George Washington Bridge, the Lincoln Tunnel and the New York building that housed the FBI.
"And he said that Americans would realize, if they suffered those type of casualties, that they were at war," Secret Service agent Brian G. Parr testified at Yousef's 1997 trial.
The terrorists discovered that a single van full of explosives would not bring down the skyscrapers, and they vowed to try again. Just four days after the 1993 bombing, a group calling itself the Liberation Army Fifth Battalion warned of additional attacks against American civilian and military targets.
"The American people must know that their civilians who got killed are not better than those who are getting killed by the American weapons and support," the letter said.
Investigators found a second letter on a suspect's computer that warned of violence against the World Trade Center. It read, "We promise you that the next time it will be very precise and WTC will continue to be one [of] our targets in the U.S."
A New York jury convicted Yousef of masterminding the 1993 bombing. He also was found guilty of a 1995 conspiracy to bomb a dozen airplanes and kill 4,000 passengers as they flew over the Pacific Ocean. The bombing of a Philippine Airlines jet in 1994 -- which killed one person -- was a reported test run.
In testimony at the Yousef trial, potential terrorists learned the twin towers could withstand being hit by a Boeing 707, so they used two heavier planes Tuesday. The two hijacked planes also hit between the 40th and 70th floors, sites calculated to produce the greatest damage.
The U.S. intelligence community is concerned that terrorists are plotting a fresh attack away from Washington and New York that does not involve a hijacked airplane.
"They are not convinced it is over," said Rep. Jane Harman (D-Calif.), a ranking member of the House Intelligence Committee. A former intelligence official added: "The community believes something suspicious is going on and there is a reason for there to be more. Americans tend to let down their guard after a couple of days."
Graham said the CIA warned there was no "specific information to lead to who, where, when," but the intelligence community advised "caution for a considerable period of time."
