On September 11, 2001, the United States suffered a series of coordinated suicide attacks perpetrated by members of the Islamic terrorist group Al Qaeda, which was then based in Afghanistan and led by Osama bin Laden. On that day, 19 Al Qaeda terrorists hijacked four commercial American jetliners and crashed them into prearranged targets. Two of the airplanes crashed into the Twin Towers of the World Trade Center in New York City. Another plane crashed into the Pentagon, the headquarters of the Department of Defense, in northern Virginia. A fourth plane crashed into a field near Shanksville in rural Somerset County, Pennsylvania, after some passengers, having been informed of the other suicide airplane attacks from cellular phone communications with family members, attempted to storm the cockpit and regain control of the plane from the hijackers. The White House or the Capitol were the most likely suspected targets of this plane. Excluding the hijackers, a total of 2,974 died in the attacks, including 246 from all four planes in which there were no survivors. The attacks crippled not only the city and economy of New York City but also sectors of the U.S. economy. Particularly hard hit were the airline and insurance industries, which suffered billions of dollars of losses. The September 11 attacks were the worst terrorist attacks ever committed against the United States, and the resulting death toll surpassed that of the December 7, 1941, Japanese attack on Pearl Harbor.

The George W. Bush administration responded to the attacks by declaring a Global War on Terror. The next month the United States invaded Afghanistan, toppling the Taliban government that Page 1096  |  Top of Articlehad given sanctuary and support to bin Laden and Al Qaeda. The U.S. government also enacted the Patriot Act in October 2001, a sweeping law designed to protect the country against terrorism by enhancing the power of the federal government to conduct criminal and intelligence investigations, engage in espionage, and conduct searches for communications records.

Fires burn amid the rubble and debris of the World Trade Center in New York City in the area known as Ground Zero two days after the September 11 terrorist attacks. (U.S. Department of Defense)

The four airliners hijacked—American Airlines Flight 11 (Boston to Los Angeles), American Airlines Flight 77 (Dulles, Virginia, to Los Angeles), United Airlines Flight 175 (Boston to Los Angeles), and United Airlines Flight 93 (Newark to San Francisco)—were all bound for the West Coast from the East Coast. Al Qaeda deliberately chose the flights because of their long distance, which meant that the large airplanes (Boeing 757s and 767s) would be carrying large amounts of jet fuel, thereby intensifying the destruction and explosions once the planes crashed. It is suspected that at least some of the hijackers had previously flown on some of the same flights from the East Coast in preparation for their suicide operations.

It is not entirely clear how exactly the hijackers gained control of the cockpits of each of the four planes, as federal aviation rules mandated that cockpit doors remain closed and locked during flight. The hijackers were armed with box cutters, however, and also mace or pepper spray. According to some passengers on some of the planes, the terrorists claimed to have bombs as well, although this was probably a ruse to control the passengers. According to the September 11 Commission Report, the hijackers probably opened the then-unreinforced cockpit doors by forcing a flight attendant to open them. Other theories hold that they may have stabbed the flight attendants to obtain a cockpit door key or somehow lured the captain or first officer out of the cockpit. During cell phone conversations as the attacks unfolded, some passengers on American Airlines Flight 11 reported that two flight attendants had been stabbed; passengers on United Airlines Flight 175 revealed that both pilots had been killed and that a flight attendant had been stabbed. However, passengers on American Airlines Flight 77 and United Airlines Flight 93 reported no in-air injuries or deaths, but the cockpit voice recorder of United Airlines Flight 93 indicated that a woman, most likely a flight attendant, was being held in the cockpit and that she struggled with one of the hijackers, who either killed or otherwise silenced her.

None of the airport security checkpoint supervisors recalled the 19 hijackers or reported anything suspicious regarding their screening. The hijackers were apparently allowed to clear security unimpeded. The September 11 Commission, however, concluded that the quality of the screening was “marginal at best,” particularly given the fact that two of the hijackers had set off metal detectors and were then hand-wanded and allowed to proceed. The security screeners never resolved what had set off the metal detector in the first place, and airport video footage showed that one of the hijackers was carrying an unidentified item clipped to his back pocket, which escaped any scrutiny. In addition, although some of the hijackers were selected by a computerized prescreening program known as Computer Assisted Prescreening Passenger System (CAPPS) to identify passengers who should be subjected to special security measures, this only meant that the hijackers’ checked bags were held off the plane until it was confirmed that they were aboard the aircraft. CAPPS did not trigger any further scrutiny of what they carried on the planes with them.

American Airlines Flight 11 and United Airlines Flight 175 crashed into the 110-story North Tower and South Tower of the World Trade Center at 8:48 a.m. and 9:30 a.m. local time, respectively. Due to massive structural failure, the South Tower collapsed at 9:59 a.m., and the North Tower collapsed at 10:26 a.m., killing a total of 2,603 in both buildings (including 341 New York firefighters and two paramedics, 23 New York City police officers, and 37 Port Authority police officers); another 24 people remain listed as missing. The collapse of the two huge buildings also brought down Page 1097  |  Top of Articleneighboring office towers and badly damaged others, all of which occurred in a densely populated part of the city.

A view of the Pentagon in Washington, D.C., one day after the terrorist attack on September 11, 2001. (U.S. Air Force)

According to a 2005 report by the National Institute of Standards and Technology of the U.S. Department of Commerce titled “Final Report on the Collapse of the World Trade Center Towers,” the impact of both planes as they crashed ignited thousands of gallons of jet fuel, which melted the thermal insulation, or fireproofing, on the interior core steel-support columns of the World Trade Center. That caused the floors to sag and then collapse. In so doing, they pulled and collapsed the exterior, or perimeter columns, of the buildings, reducing their ability to support the floors above. This explains why neither tower collapsed immediately upon impact with the aircraft. The aircraft impacts did not cause the towers to collapse; instead, it was the ensuing fires from the exploding jet fuel that ultimately brought the buildings down. The South Tower collapsed more quickly than the North Tower because there was more aircraft damage to the central core of the South Tower, which then collapsed the exterior or perimeter support structure of that building. The report also found no evidence to substantiate some of the principal conspiracy theories alleging that the World Trade Center was destroyed by some elements of the U.S. government by means of a controlled implosion using explosives.

Meanwhile, American Airlines Flight 77 crashed at 9:37 a.m. local time into the Pentagon, killing 125 people, while United Airlines Flight 93 plowed into a field in Shanksville, Pennsylvania, at 10:03 a.m., killing all 40 passengers and crew aboard. It is clear from the cockpit voice recorder that the hijackers, who had gained access to the plane's controls, were aware of the passengers’ assault against the cockpit and pitched the plane so that it crashed into an empty field.

The motives for the attacks of September 11, 2001, date from Al Qaeda's declaration of jihad (holy war) against the United States in February 1998. Bin Laden decried American foreign policy in the Middle East including America's military presence in Saudi Arabia, the site of Islam's two holiest shrines. According to bin Laden, American support for Israel and dictatorial Arab states such as Egypt and Saudi Arabia allegedly constituted proof of anti-Islamic U.S. policies. Sadly, the attacks of September 11, 2001, were but a tragic and devastating culmination of escalating attacks by Al Qaeda against U.S. targets around the world, including the August 1998 U.S. embassy bombings in Kenya and Tanzania and the October 2000 attack on USS Cole in a Yemeni port.

The fallout from the attacks was both long lasting and far reaching. No commercial air traffic was allowed for several days after the attacks, the stock market was closed for nearly a week, and the U.S. economy tilted toward recession as consumer spending plummeted in the weeks and months after the disaster. The attacks helped shape the Bush Doctrine, which would seek to Page 1098  |  Top of Articleprevent further attacks by launching preemptory strikes against nations or regimes likely to launch terrorist assaults on the United States. The 2003 invasion of Iraq was a case in point. The Iraq War and the Afghanistan War have both dragged on, without resolution. Finally, the September 11 attacks shattered Americans’ sense of invulnerability, which has helped the federal government erect a pervasive and powerful internal security state to complement the broader national security state.