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By Tuesday afternoon, the spooks were making progress. Eavesdroppers at the supersecret National Security Agency had picked up at least two electronic intercepts indicating the terrorists had ties to bin Laden. By nightfall, less than 12 hours after the attacks, U.S. officials told TIME that their sense that he was involved had got closer to what one senior official said was 90%. The next morning, U.S. officials told TIME they have evidence that each of the four terrorist teams had a certified pilot with them; some of these pilots had flown for an airline in Saudi Arabia and received pilot training in the U.S. It's not yet clear whether the pilots were trained in the U.S., or in Saudi Arabia or both. Intelligence officials believe each team had four to six persons. Some team members, it is thought, crossed the Canadian border to get into the U.S. Sources told TIME that within the past few months, the FBI added to the U.S. watch list two men whom the bureau believed to be associated with one of the Islamic Jihad terror groups. Through a screwup, the suspects were lost. The two men appear to have been on the American Airlines Flight 77, the plane that crashed into the Pentagon, sources told TIME. Boston appears to have been a central hub for the operation; U.S. intelligence believes a bin Laden cell in Florida was a support group helping with the aviation aspects of the attack.
Intelligence officials poring over old reports believe they got their first inkling of planning for the attack last June, although at the time the intelligence was too vague to indicate the scale of the operation. In the summer U.S. embassies, particularly those in the Middle East, were put on heightened alert, as was the U.S. military in the region. The CIA was getting vague reports "of some kind of spectacular happenings" by terrorists, said a U.S. intelligence official, but the reports were vague as to timing. "A lot of this reporting we had in the summer that gained our attention and had us concerned, but wasn't specific, could have been tied to this," said a U.S. intelligence official.
Even had they known more, could officials ever have contemplated the scale of this thing? The blasts were so powerful that counterterrorism teams have begun asking the airlines for fuel loads on the plane; aviation experts have been asked to calculate the explosive yield of each blast in kiloton terms. The reason? Washington wants to see if the planes amounted to weapons of mass destruction. "What we want people to realize is they've crossed a line here," said a U.S. intelligence official. In fact, some senior Administration officials are considering drafting a declaration of war, although the State Department is leery since nobody knows precisely who the war would be against.
By contrast, as the day unfolded, it looked awfully easy to declare war on us. The attack was the perfect mockery of the President's faith in missile defense: What if the missile is an American Airlines plane, and the pilot wants to kill you? It was only eight years ago that a group of zealots led by Ramzi Yousef tried to take the towers down from the bottom, with a rented Ryder truck full of homemade explosives. Their goal, as an unsigned statement presented later at trial put it, was no less than toppling "the towers that constitute the pillars of their civilization."