Tower Terror

AMERICANS WERE NOT ACCUSTOMED to what so much of the world had already grown weary of: the sudden, deafening explosion of a car bomb, a hail of glass and debris, the screams of innocent victims followed by the wailing sirens of ambulances. Terrorism seemed like something that happened somewhere else -- and somewhere else a safe distance over the horizon.

And then last week, in an instant, the World Trade Center in New York City became ground zero.

At 12:18 on a snowy Friday afternoon, a massive explosion rocked the foundation of the Twin Towers of the Trade Center in lower Manhattan -- the second tallest buildings in the world and a magnet for 100,000 workers and visitors each day. The bomb was positioned to wreak maximum damage to the infrastructure of the building and the commuter networks below. And the landmark target near Wall Street seemed chosen with a fine sense for the symbols of the late 20th century. If the explosion, which killed five people and injured more than 1,000, turns out to be the work of terrorists, it will be a sharp reminder that the world is still a dangerous place. And that the dangers can come home.

Against that threat, the relevant intelligence agencies mobilized quickly. The news from New York sent the FBI and other federal agencies to Code Red, their highest state of readiness. The FBI activated its Joint Terrorist Task Force, and the CIA turned up the heat at its Counterterrorist Center in Langley, Virginia, a conglomerate of psychiatrists, explosives experts and hostage negotiators. Meanwhile, the Bureau of Alcohol, Tobacco and Firearms, the agency responsible for investigating the loss and theft of explosives, mobilized its 13-member National Response Team held on 24-hour call in the New York area. They were joined by bureau chemists from headquarters in Rockville, Maryland.

Until it is firmly concluded that a terrorist was responsible, the New York City police department is in charge, and it was the N.Y.P.D. that took the lead in sifting through the 19 telephoned claims of "credit" that were received in the first 24 hours. Though none came in before the blast -- the earliest followed it by an hour, well after the first news reports -- a few were intriguing. Many of the calls were made by people claiming to be affiliated with Balkan groups, including one made by a caller in Europe who said he represented the Black Hand, a Serbian extremist organization last active about 10 years ago. According to terrorism expert Xavier Raufer, Serbian nationalists have threatened terrorist reprisals against West European countries for interference in the region.

There were immediate suspicions that Bill Clinton's decision last week to air-drop relief supplies over Bosnia -- a step that had seemed like a low-risk humanitarian gesture -- might have been answered in thunder by the Serbs. Still, the Bosnian hypothesis was by no means the only one. A caller from the West Coast credited the Iranian Revolutionary Guard; an anonymous tipster blamed Jewish extremist groups.

Because of their trouble getting to the "blast seat" in the dangerously crumbling underground garage, investigators could not even confirm to their complete satisfaction what had caused the explosion. But its size and intense heat suggested a bomb, as did traces of nitrate found at the edges of the blast crater. Until they could determine otherwise, informed experts assumed that hundreds of pounds of high explosives had been packed into a car or van that was left at a four-level underground parking garage. The garage is situated below the Trade Center plaza and near a station of the PATH commuter subway line that links Manhattan and New Jersey.

The Trade Center is not a surprising target. In the early 1970s CIA agents compiled a list of potentially vulnerable sites that they believed might make high-value terrorist strike points. Near the top of that list, former deputy CIA director Bobby Inman told TIME, was the World Trade Center. "When the people responsible for anticipating terrorist attacks began to run scenarios on this kind of thing, this was one of the places." Why? "Because of the number of victims who would be involved," said Inman. The information raises questions about what kind of extra precaution the Port Authority might have taken in light of the building's tantalizing vulnerability.

The bomb blew out a crater 200 ft. by 100 ft. wide and five stories deep. Floors collapsed onto one another with an impact that caused the ceiling of the PATH station nearby to come crashing down, showering chunks of concrete onto commuters waiting on the platform. In the same moment, the 110-story Twin Towers swayed visibly as the force of the blast shuddered upward. Lobby windows exploded onto the plaza and marble slabs fell from the walls. As fractured steam pipes launched jets of hot mist into the air, the first victims stumbled out of the buildings, bloodied and in shock.

Fires quickly broke out, launching thick, acrid smoke up hundreds of stairwells and elevator banks. In both towers the electricity went out, including emergency backup systems. Even on the highest floors, workers were stunned by the speed at which smoke flew upward. David Deshane, 25, was on the 105th floor when he felt the explosion. "All the computers shut down, then all the phones shut down," he said. "Then all of a sudden we saw smoke ( everywhere." He ran to hit the fire-emergency button. "Nothing happened." In a panic, some people broke windows to admit air, sending daggers of glass raining onto the crowds below and creating a chimney effect that drew smoke upward even more quickly.

Four of the dead were Port Authority workers, whose offices and locker rooms were located on the lower levels that sustained the worst damage. More than 24 hours after the blast, two other workers were still missing. But the toll was less severe than first feared. Though some suffered major injuries, most of the victims were treated for smoke inhalation or minor burns.

In a meeting late Friday evening, the state and federal agencies involved in the case hammered out a protocol to govern the inquiry. The first priority was to stabilize the pillars that hold up the Vista Hotel on the Trade Center plaza and which were supported in turn by the garage floors that were ripped away in the blast. Before investigators can safely enter the blast site, workers must buttress the dangerous sagging remnants of the garage and lay a web of tubular steel beams across the crater left by the bomb. It may be days before investigators can begin to sift through the tons of debris for clues to the bomber.

Then the hard work begins. Once they enter the damaged area, investigators will face the tedious process of finding chemical traces and fragments of the vehicle to help identify the type of bomb. Most well-known terrorist groups have their own "signatures" -- characteristic explosive compounds, detonators and even device designs. If investigators find enough clues, "they can detect who made this particular bomb," says Professor Robert Phillips, an expert in terrorism at the University of Connecticut. "They're able to detect even individual bombmakers' ways of doing things, of placing wires, of placing fuses, how they put the whole thing together. There aren't lots of people in the world who do this well." At the top of Phillips' suspect list are Middle Eastern and Balkan terrorists. Says Phillips: "The car bomb is very much the signature of these groups."

According to Inman, the sheer difficulty of constructing bombs of this nature almost rules out an American-made device. "There hasn't been a domestic development of the kind of skills that are needed for this, as there has been in Northern Ireland or the Middle East," says Inman.

Outside experts liken the task of identifying the Trade Center bomb to the inquiry into the bombing of Pan Am Flight 103, in which debris was scattered for miles. Investigators in that case drew a life-size diagram of the plane on a warehouse floor, then set about reconstructing it piece by piece like a jigsaw puzzle. From that they could determine where in the plane's body the blast occurred, because "the metal would be bent to follow the contours of the vectors of the explosion," says Phillips.

Though the FBI does not yet know whether enough evidence is left to piece together the car bomb it believes was there, its experts plan to move large quantities of debris to a secure location and examine it with microscopic care. They will search for tiny remnants that don't really belong at the scene -- that are not, say, part of a car's headlights or dashboard. Items as small as a bit of wire can point to whether a timing device was used.

The whole area will also be examined for chemical residue, which will help in determining what kind of explosive was used. In car bombings, bits of explosive matter are often found in the nooks and crannies of what is left of the auto's trunk lid. Nitrate, traces of which were found in the Trade Center crater, is the most basic component of most explosive mixtures. The next step is to find traces of chemicals that may be unique to a certain compound, like potassium or ammonium, which would identify the explosive far more precisely.

Experts will also try to determine the velocity of the shock waves emanating from the blast. "Different compounds explode at different speeds," says Brian Jenkins, senior managing director for Kroll Associates, an international investigating firm. "You can tell by examining the metal that was torn apart. Was it a big explosion that moved a lot of things, or was it a high-velocity explosion that rent metal?" Sophisticated plastic explosives tend to shred metal and pulverize concrete, while common substances like dynamite tend to knock walls over and push vehicles around. Once investigators identify the substance, they will try to determine whether it was a homemade explosive, one made from commercially available material or a product of limited availability, like a military-grade explosive. If the material is common, the trail may be colder than if it is a closely monitored substance.

Initial speculation in this case centers upon plastic explosives like Semtex, the lethal weapon of choice for many terrorists because it is safe to - handle and undetectable by sniffer dogs or X-ray inspection. A small amount hidden in a portable radio blew Pan Am Flight 103 out of the sky in 1988. Semtex was produced in quantity under the communist government of Czechoslovakia; while the postcommunist Czech Republic has discontinued production, large quantities remain in the hands of terrorist gangs that obtained them illicitly. Three years ago, Czechoslovak President Vaclav Havel estimated that "world terrorism has supplies of Semtex to last 150 years."

Until last week, federal agents were confident that terrorist groups contemplating action on American soil would have considerable difficulty smuggling in enough high explosives to manufacture a sizable car bomb. Could they have obtained them in the U.S.? Although high explosives are widely used in the construction industry, they are monitored. The FBI maintains close contacts with manufacturers and dealers, while sales are tightly regulated by the Bureau of Alcohol, Tobacco and Firearms. Though the Pentagon possesses its own plastic explosive, a Semtex relative called C-4, a would-be terrorist would have to steal it from a military facility -- a theft that would probably be detected. Other explosives might be simpler to accumulate, however, like ammonium nitrate, an ordinary component of fertilizer that has been a favorite of the Irish Republican Army.

Experts speculate that the bomb may have consisted of several hundred pounds of high explosives. The bomber may have known that because the device would be detonated in the reinforced enclosure of a garage, it would deliver more bang for the buck. An enclosed area can double the "shock wave" value of an explosion. "When you have a contained explosion, the blast doesn't vent," says Phil Hough, president of International Explosives Disposal (USA). "Effectively the building becomes part of the bomb." Says Phillips: "The garage was the perfect location because of both the damage to the upper floors ((with smoke)) and structural damage the bomb would cause at the base."

Once more is known about the methods and materials of the bomber, federal agencies can compare them with the details of past bombings that are stored on its computer data base. There is also a massive job ahead of identifying and interviewing witnesses who may have seen something in the parking garage or the building. And the FBI is intensifying surveillance of possible terrorist groups and foreign agents suspected of involvement in the bombing. The bureau . has also infiltrated potential terrorist groups in this country, as the CIA has done overseas. Those contacts can now be used to gather leads. "You're going to have to depend on informants," says former CIA official David Whipple. "And you almost always have informants."

Investigators will look at every possible motive, from Balkan nationalism to employee dissatisfaction at the Trade Center. "You can't take just one track, because you come to dead ends and you've lost time," says an FBI official. "You have to investigate multiple tracks at the same time." Eventually, with luck, the pieces start coming together. "Some of it is misinformation, some of it is disinformation," says Jenkins, "and some small portion is information. You have to sort all that out. In the ideal situation, these paths begin to converge. You get a chain of physical evidence that takes you all the way from the debris back to the perpetrator."

Will the perpetrator be carrying a flag? Says former CIA Director Robert Gates: "It's always been a possibility that, as ethnic conflicts spread, the losers might try to exact some sort of price, to attract attention to their cause." But it was by no means certain last week that the Trade Center bombing was an act of political terrorism. During the Gulf War, a bomb found on a chemical storage tank in Virginia instantly raised an alarm. The culprit turned out to be a businessman who hoped to make an insurance-fraud fire look like the work of Iraqis.

Yet even before the answers were in as to who had planted the bomb, a new question -- whether a season of terrorism might begin in the U.S. -- had been raised. In the wake of the explosion, bomb threats forced the evacuation of the Empire State Building and Newark airport. Both threats were false, but no one was ready to dismiss the likelihood of another assault. Around the country, airports and other public facilities stepped up security. The blast was a reminder of the vulnerability of most American office buildings, shopping malls, airports and railway stations. Even the U.S. government has let its guard down since the mid-1980s, when American installations were on constant alert and concrete barriers were set up around many government buildings n Washington.

"International terrorism in the '80s was fundamentally fueled by the cold war," says Phillips, "and you can almost date the diminution of that terrorism with Gorbachev's ascension to power." But the end of communism has $ helped ignite the fires of nationalism in regions like the Balkans, emboldening other fanatical groups to sow the kind of trouble once created by Soviet and East bloc terrorists.

As the only remaining superpower, the U.S. can find itself the target of resentments of players on all sides who are seeking American involvement or trying to fend it off. Massive car bombs have become familiar as political weapons in the Middle East and Europe. But it would represent a quantum leap in terrorist capabilities -- and brazenness -- to assemble one in the U.S. Middle East terror networks, for one, have never shown themselves to be capable of that or interested in doing so, preferring to concentrate their attacks on Westerners in Europe, where they have found it easier to operate.

Whoever the bomber was, he made an indelible statement. On top of the deaths and injuries, the bomb's damage to the heart of New York City's financial district will bring heavy costs. Repairs and restoration alone will cost the Port Authority as much as $100 million, according to one estimate. But the disruption to business will be even worse, because the Port Authority will have to close the giant complex for at least several days for structural and safety work. The towers, which represent about 10% of all the office space in Manhattan's financial district, are so large that they have two ZIP codes.

Perhaps the most unsettling possibility is that the hand behind the blast will never reveal itself and never be discovered by anyone else. Though two Libyan intelligence agents were indicted in the downing of Pan Am 103, they have never been brought to trial, and no nation or group ever came forward to take responsibility. Just blocks from the World Trade Center, the walls of the Morgan Guaranty Trust Co. are still scarred from the effects of a bomb that was hidden in a horse-drawn wagon on Sept. 16, 1920. When it exploded into a lunchtime crowd, 40 people died and 200 were injured. The mystery of the blast was never cleared up. The investigators who have begun scratching through the rubble of the Trade Center are determined that this flash of terror will not go unsolved.