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Homeland Security

World Trade Center and Pentagon Attacks

The largest scale international terrorist attack ever-involving four separate but coordinated aircraft hijackings-occurred in the United States on September 11, 2001. The 19 hijackers belonged to the al-Qaida terrorist network. According to investigators and records of cellular phone calls made by passengers aboard the planes, the hijackers used knives and boxcutters to kill or wound passengers and the pilots, and then commandeer the aircraft, which the hijackers used to destroy preselected targets.

  • Five terrorists hijacked American Airlines flight 11, which departed Boston for Los Angeles at 7:45 a.m. An hour later it was deliberately piloted into the North Tower of the World Trade Center in New York City.
  • Five terrorists hijacked United Airlines flight 175, which departed Boston for Los Angeles at 7:58 a.m. At 9:05 the plane crashed into the South Tower of the World Trade Center. Both towers collapsed shortly thereafter, killing approximately 3000 persons, including hundreds of firefighters and rescue personnel who were helping to evacuate the buildings.
  • Four terrorists hijacked United Airlines flight 93, which departed Newark for San Francisco at 8:01 a.m. At 10:10 the plane crashed in Stony Creek Township, Pennsylvania killing all 45 persons on board. The intended target of this hijacked plane is not known, but it is believed that passengers overpowered the terrorists, thus preventing the aircraft from being used as a missile.
  • Five terrorists hijacked American Airlines flight 77, which departed Washington Dulles Airport for Los Angeles at 8:10 a.m. At 9:39 the plane was flown directly into the Pentagon in Arlington, Virginia, near Washington, D.C. A total of 189 persons were killed, including all who were onboard the plane.

More than 3000 persons were killed in these four attacks. Citizens of 78 countries perished at the World Trade Center site.

The attacks were the fruition of years of planning by Islamic militants declaring allegiance to al-Qaeda and Usama Bin Ladin. By late 1998 or early 1999, Bin Ladin and his advisers had agreed on an idea brought to them by Khalid Sheikh Mohammed (KSM) called the "planes operation." It would eventually culminate in the 9/11 attacks. Bin Ladin and his chief of operations, Mohammed Atef, occupied undisputed leadership positions atop al Qaeda. Within al Qaeda, they relied heavily on the ideas and enterprise of strong-willed field commanders, such as KSM, to carry out worldwide terrorist operations.

KSM claims that his original plot was even grander than those carried out on 9/11-ten planes would attack targets on both the East and West coasts of the United States. This plan was modified by Bin Ladin, KSM said, owing to its scale and complexity. Bin Ladin provided KSM with four initial operatives for suicide plane attacks within the United States, and in the fall of 1999 training for the attacks began. New recruits included four from a cell of expatriate Muslim extremists who had clustered together in Hamburg, Germany. One became the tactical commander of the operation in the United States: Mohamed Atta.

By the summer of 2000, three of the four Hamburg cell members had arrived on the East Coast of the United States and had begun pilot training. In early 2001, a fourth future hijacker pilot, Hani Hanjour, journeyed to Arizona with another operative, Nawaf al Hazmi, and conducted his refresher pilot training there. A number of al Qaeda operatives had spent time in Arizona during the 1980s and early 1990s. dator.

During the spring and summer of 2001, U.S. intelligence agencies received a stream of warnings that al Qaeda planned, as one report put it, "something very, very, very big." Director of Central Intelligence George Tenet told us, "The system was blinking red."

Although Bin Ladin was determined to strike in the United States, as President Clinton had been told and President Bush was reminded in a Presidential Daily Brief article briefed to him in August 2001, the specific threat information pointed overseas. Numerous precautions were taken overseas. Domestic agencies were not effectively mobilized. The threat did not receive national media attention comparable to the millennium alert.

Though the "planes operation" was progressing, the plotters had problems of their own in 2001. Several possible participants dropped out; others could not gain entry into the United States (including one denial at a port of entry and visa denials not related to terrorism). One of the eventual pilots may have considered abandoning the planes operation. Zacarias Moussaoui, who showed up at a flight training school in Minnesota, may have been a candidate to replace him.

As final preparations were under way during the summer of 2001, dissent emerged among al Qaeda leaders in Afghanistan over whether to proceed. The Taliban's chief, Mullah Omar, opposed attacking the United States. Although facing opposition from many of his senior lieutenants, Bin Ladin effectively overruled their objections, and the attacks went forward.

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Page last modified: 13-07-2011 12:49:09 ZULU