1993 World Trade Center bombing

On February 26, 1993, a large truck bomb detonated in a parking garage of the World Trade Center. It was not a suicide attack, but a timed device in a rented truck. The explosion blew a hole seven stories up into the building and caused casualties all over it, but only six deaths but over 1000 injured. The attack was planned and carried out by jihadists, although a loose association of Islamist terrorists, a number with associations to the Services Office, a group supporting the mudjahadeen fighting the Soviets in the Afghanistan War (1978-1992); members of this organization would later be among the founders of al Qaeda. While Richard Clarke suggests the operation was conducted by al-Qaeda, that organization was still being formed in 1993.

The investigation, under the Federal Bureau of Investigation (FBI), with the assistance of the United States intelligence community, quickly identified the attackers. Ironically, the effectiveness of their response has been suggested as having given complacency that conventional law enforcement could protect against future terrorism. An unfortunate consequence of this superb investigative and prosecutorial effort was that it created an impression that the law enforcement system was well-equipped to cope with terrorism.

Major findings of the 9/11 Commission included:
 * 1) "The bombing signaled a new terrorist challenge, one whose rage and malice had no limit. Ramzi Yousef, the Sunni extremist who planted the bomb, said later that he had hoped to kill 250,000 people.
 * 2) The FBI and the Justice Department did excellent work investigating the bombing. Within days, the FBI identified a truck remnant as part of a Ryder rental van reported stolen in Jersey City the day before the bombing.

Investigation and arrest
Mohammed Salameh, who had rented the truck and reported it stolen, kept calling the rental office to get back his $400 deposit. The FBI arrested him there on March 4, 1993. In short order, the Bureau had several plotters in custody, including Nidal Ayyad, an engineer who had acquired chemicals for the bomb, and Mahmoud Abouhalima, who had helped mix the chemicals.

The FBI identified another conspirator, Ahmad Ajaj, who had been arrested by immigration authorities at John F. Kennedy International Airport in September 1992 and charged with document fraud. His traveling companion was Ramzi Yousef, who had also entered with fraudulent documents but claimed political asylum and was admitted. Yousef, fled to Pakistan immediately after the bombing and would remain at large for nearly two years.

The arrests of Salameh, Abouhalima, and Ayyad led the FBI to the Farouq mosque in Brooklyn, where a central figure was Sheikh Omar Abdel Rahman. Often called the "Blind Sheikh," Rahman preached the message of Sayyid Qutb's Milestones, characterizing the United States as the oppressor of Muslims worldwide and asserting that it was their religious duty to fight against God's enemies. This group was planning attacks on other New York targets, and additional arrests were made in June 1993.

In the later trial, the government presented evidence that additional conspirators were involved. Ajaj had materials pointing to activities at the Khaldan training camp on the Afghanistan-Pakistan border. Ajaj had left Texas in April 1992 to go there to learn how to construct bombs; He had met Ramzi Yousef in Pakistan.