2 The bomb

Yousef's complex 600 kilogram bomb was made of urea pellets, nitroglycerin, sulfuric acid, aluminum azide , magnesium azide , and bottled hydrogen. He added sodium cyanide to the mix as the vapors could go through the ventilation shafts and elevators of the towers. The van that Yousef used had four 6 m (20 ft) long fuses, all covered in surgical tubing. Yousef calculated that the fuse would trigger the bomb in twelve minutes after he would use a cheap cigarette lighter to light the fuse.

He wanted to prevent smoke from escaping the towers, therefore, catching the public eye by poisoning people inside. He foresaw Tower One collapsing onto Tower Two after the blast would occur.

3 The attack

On February 26, 1993, a car bomb was planted by Islamist terrorists in the underground garage below Tower One. The bomb's fuses burnt at a rate of one inch per two and one half seconds (1 cm/s). The men spent 300 United States dollars for the materials to build the bomb.

The bomb exploded in the underground garage at 12:17 P.M., opening a 30 meter wide hole through 4 sublevels of concrete. The bomb generated a pressure of more than 1 GPa. The detonation velocity of this bomb was about 4.5 km/s (15,000 ft/s). The cyanide gas that Yousef put in the bomb burnt up in the explosion.

Six people were killed. At least 1,040 others were injured. However, the towers were not destroyed as Yousef envisioned. Yousef escaped to Pakistan several hours later.

The bomb cut off the center's main electrical power line, and all telephone service for New York City. The bomb caused smoke to rise up to the 93rd floor of both towers, and cut off the towers' four stairwells and emergency lighting system. Also as a result of the loss of electricity most of New York City's radio and television stations lost their over-the-air broadcast signal for almost a week with television stations only being able to broadcast via cable and satellite via a microwave hookup between the stations and three of the New York area's largest cable companies, Cablevision , Comcast and Time Warner Cable .

Despite its relatively low death toll, the bombing shocked the American public. Only once before the 1993 attack that the FBI recorded had a bomb of that force had been used. The FBI has recorded a total of about 73,000 explosions.

Yousef's friends reported the van stolen in an attempt to slow investigators down.

3.1 List of deceased

• John DiGiovanni, Valley Stream, New York
• Robert Kirkpatrick, Suffern, New York
• Steve Knapp, Manhattan, New York, New York
• Monica Smith, Seaford, New York
• William Macko, Bayonne, New Jersey
• Wilfredo Mercado, Brooklyn, New York, New York.

4 After the attacks

On March 4, 1993 authorities announced the capture of one of the suspected bombing conspirators Mohammad Salameh and exactly one year later four terrorists were convicted for their roles in the bombing.

The capture of Salameh led authorities to Yousef's apartment, where they found bomb-making materials and a business card from Mohammed Jamal Khalifa.

Khalifa was arrested in relation to the crime in December 14, 1994, and was deported to Jordan by the INS in May 5, 1995. He was acquitted by a Jordanian court and now lives as a free man in Saudi Arabia.

In 1995, militant Islamist Sheik Omar Abdel-Rahman and nine others were convicted of conspiracy charges to bomb several New York City landmarks (see New York City landmark bomb plot), and in 1998, Ramzi Yousef, believed to have been the mastermind, was convicted of "seditious conspiracy" to bomb the towers - no one was ever convicted for the actual bombing. Another man named Eyad Ismail was tried alongside Yousef for the bombing.

Six militant Islamist conspirators were convicted of the crime in 1997 and 1998 and given prison sentences of a maximum of 240 years each. The main reason that the World Trade Center did not collapse was due to the towers' strength and the fact that Yousef did not have enough money to build a more powerful bomb.

Another conspirator in the plot was Nidal Ayyad .

A granite memorial to the six victims of the bombing was erected between the Twin Towers, directly above the site of the explosion. This granite memorial erected in memory of the first attack was obliterated during the destruction of the towers in 2001.

5 FBI foreknowledge

In the course of the trial it was revealed that the FBI had an informant, an Egyptian man named Emad Salem , who was involved with the bombing conspiracy. Salem claims to have informed the FBI of the plot to bomb the towers as early as February 6, 1992, information he was privy to possibly because he himself initiated the plot. Salem's role as informant allowed the FBI to quickly pinpoint the conspirators out of the hundreds of possible suspects.

Salem asserts that the original plan was to have the plotters build the bomb using a harmless powder instead of actual explosive, but that an FBI supervisor decided that a real bomb should be constructed instead. He substantiates his claims with hundreds of hours of secretly-recorded conversations with his FBI handlers, made during discussions held after the bombings.

Salem says he wished to complain to FBI headquarters in Washington about the failure to prevent the bombing despite foreknowledge, but was dissuaded from doing so by the New York FBI office.

The FBI has not explicitly denied Salem's account.

6 See also

• terrorist incidents
• New York City landmark bomb plot
• Operation Bojinka
• Background history of the September 11, 2001 attacks

7 Further reading

The New Jackals by Simon Reeve

8 Reference

• Ralph Blumenthal, Tapes Depict Proposal to Thwart Bomb Used in Trade Center Blast, New York Times, Thursday October 28 (1993) p. A1; online edition by www.whatreallyhappened.com

New York City history Terrorist incidents World Trade Center

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