A Bridge Under Scrutiny, by Plotters and the Police

Al Qaeda has long had a fascination with suspension bridges, especially the Brooklyn Bridge. New documents reveal that before Sept. 11, 2001, methods for bringing down bridges were being taught at a terrorist training camp in Afghanistan.

After 9/11, Khalid Shaikh Mohammed, the admitted mastermind of the attacks, got even more specific, telling an operative, Iyman Faris, to “destroy the Brooklyn Bridge by cutting the suspension cables,” according to a 2006 assessment of Mr. Mohammed that is among the hundreds of classified Guantánamo files made available recently to The New York Times.

The Brooklyn Bridge plot was revealed in 2003 with the arrest of Mr. Faris, a naturalized American citizen from Kashmir.

But the brief reference in the report on Mr. Mohammed hints at the impact of the aborted plot on security in New York and on the bridge in particular. Today, the bridge is one of the most carefully guarded potential targets in New York — maintenance crews, for example, must notify the Police Department’s Intelligence Division before scaling the cables.

Security cameras watch hidden corners of the bridge. Other measures, like police cars stationed on entry ramps, are there for all to see. To at least some extent, that is the legacy of the plot, no matter how far-fetched it might have seemed at the time.

In fact, the Police Department realized it was not far-fetched at all. After Mr. Faris’s arrest, Police Commissioner Raymond W. Kelly visited an isolated room near where the thick cables split into several thinner cables and are anchored on the shore. A vulnerability, he said, had been detected.

“I, myself, climbed down and looked at the room where the cables came together, after the Faris plot,” Mr. Kelly said. Someone could enter that room, he said, and “cut or physically weaken the center cables of the bridge.”

“If you look through all the components of it,” he added, “it was doable.”

The newly revealed Guantánamo assessments, obtained last year by the group WikiLeaks and provided by another source to The Times, show that those who mentioned bridges as possible targets were among the most high-profile Qaeda operatives, like Mr. Mohammed and Abu Zubaydah.

An assessment of Mr. Zubaydah says he provided interrogators with a list of potential Qaeda targets, including “U.S. symbols” like the Statue of Liberty, the United Nations building and “major hanging bridges,” the report says.

It was an Egyptian detainee named Tariq Mahmoud Ahmed al Sawah who told interrogators about a course in improvised explosive devices given at the training camp, where he learned about “methods to destroy suspension bridges,” his assessment says.

References to the Brooklyn Bridge were being picked up by intelligence officers in the Police Department before 9/11. Images of the bridge appeared, for example, in the backgrounds of prerecorded memorial messages left behind by suicide attackers overseas. After 9/11, said Paul J. Browne, the chief police spokesman, the department hired an engineer to study the ways the bridge could be taken down.

Karen J. Greenberg, executive director of the Center on Law and Security at New York University, said the reference to the Brooklyn Bridge in Mr. Mohammed’s file underscored the bridge’s importance as a target — as a symbol and because of the potential “for disrupting the commercial fabric of the city.”

“You get a sense from these of how Al Qaeda was thinking,” Ms. Greenberg said. “It’s akin to blocking the port in a way. It’s a major point of entry.”

In addition to the police cars on the ramps, a police boat is always nearby in the East River, with officers keeping their eyes on the bridge. Those measures were put into place after 9/11, and Mr. Kelly has said he believed they deterred Mr. Faris. Indeed, it was reported at the time that Mr. Faris, after checking on the bridge, informed Mr. Mohammed that the plot was not going to work.

“We believe that he saw what we had done, in terms of additional coverage, the radio cars on both ends of the bridge and the boat in the water,” Mr. Kelly said. “And his message back was ‘The weather is too hot,’ as I understand it.”

The police have also locked the hidden access point to the bridge’s cables. Security cameras are aimed around the clock on that spot because it was believed a saboteur would need just 15 minutes of sustained cutting with a heavy-duty gas-powered saw to sever a few of the thinner cables and undermine the bridge, law enforcement officials said. Even routine maintenance is controlled. “If legitimate maintenance has to be done,” Mr. Browne said, “the Intelligence Division has to be notified.”