zh-cn:九一一恐怖袭击事件 zh-tw:九一一恐怖襲擊事件

The September 11, 2001 attacks, often referred to as September 11 or 9/11 (after the U.S. style of writing that date, and pronounced "nine eleven"), were a series of coordinated suicide attacks against targets in the United States on September 11, 2001 that involved the hijacking of four commercial airliners. The attackers are widely believed to have been from Al Qaeda, a militantly hardline Islamic organization widely considered a terrorist group.

The jets were used as flying bombs to kill 2,995 people on that Tuesday morning at the World Trade Center, the Pentagon and a Pennsylvania field. In addition to the loss of life, the twin towers of the World Trade Center and five other buildings in New York City were destroyed or partially collapsed, 23 additional buildings nearby were damaged, and a portion of the Pentagon was also severely damaged. The event led to a "War on Terrorism" that included the U.S. invasion of Afghanistan (with support of the U.N). It was also evoked to generate domestic support for the U.S. invasion of Iraq (without support of the U.N.), and increased pressure on groups accused of being terrorists by the United States governments and countries that harbor them.

A view of the just-collapsed World Trade Center site

Table of contents
1 Overview
2 Effects
3 Cleanup
4 Responsibility
5 Investigations
6 List of topics
7 External links


It was the deadliest act of terrorism against the United States and one of the deadliest attacks of asymmetric warfare in history. On the morning of September 11, 2001, four passenger jets were hijacked over the United States. American Airlines Flight 11 crashed into the north side of the north tower of the World Trade Center at 8:46 EDT. At 9:03 AM EDT, United Airlines Flight 175 crashed into the south tower. American Airlines Flight 77 crashed into the Pentagon at 9:37 AM EDT. Both 110-story towers of the World Trade Center collapsed along with several neighboring buildings, and part of the Pentagon was destroyed by fire.

The fourth hijacked plane, United Airlines Flight 93, crashed in a Pennsylvania field. The evidence suggests that it crashed after passengers and crew tried but failed to retake control of the plane from the hijackers.

Casualties were in the thousands: 265 on the planes; at least 2,605 people, including 343 firefighters and an unknown number of undocumented workers, at the World Trade Center; and 125 at The Pentagon. Additionally at least 3,000 filed claims for compensation because of injuries caused in the attacks.

Some passengers were able to make phone calls from the doomed flights. They reported that there was more than one hijacker on each plane (a total of 19 were later identified) and that they took control of the planes using box-cutter knives. Other weapons that may have been used on at least one flight include bombs and some form of noxious chemical spray, such as tear gas or pepper spray.


The attacks of September 11th, 2001 had immediate and overwhelming effects upon the United States population and prompted numerous memorials and services all over the world, as well as support and/or tolerance for the US retaliation upon those accused of supporting the attacks. Gratitude toward uniformed public-safety workers (especially toward fire-fighters) was widely expressed in light of both the drama of the risks taken on the scene and the high death toll among them. (These were exceptional as to number compared to typical disasters, as to the ratio to civilian deaths, and as to the fraction of Manhattan emergency personnel killed.) The digits of "9/11" (the American shorthand for the date) corresponded to those of the US-wide phone number for emergency services, 911 (pronounced "nine-one-one"). (There was some initial speculation that this correspondence was intentional, to communicate something along the lines "Starting now, life in America is about emergencies rather than ease". Most Americans seemed to quickly accept press commentators' opinion that mere coincidence would be more in keeping with Islamist radicals' practice.) The coincidence in any case has emotional resonance, and may contribute as much as slips of the tongue to Americans sometimes saying "911" when they mean "9/11". Subconscious awareness of it may also contribute to the enhanced identification with public-safety personnel.

Numerous locations and events were affected by closures, postponements, cancellations, and evacuations. Political effects included legislation such as the USA PATRIOT Act and budget reforms (including the freezing of bank accounts suspected of use by people accused of being terrorists) as part of ongoing cooperation with foreign governments to arrest people in other countries, and to examine their possible involvement in terrorist rings.

On the day of the attacks, the US media reported celebration in some communities hostile to US policies, which fueled the already widespread belief that followers of Islam were to blame for the attacks. Newsweek told the story of a Muslim who had to leave the US, where she was being educated, due to racist treatment by her white peers. She points out that the Qur'an reminds its followers that "God loves not aggressors", and that the 9/11 attacks were not a jihad according to her interpretation.

Rescue and recovery took months, with the clean up continuing through May. Many relief funds were immediately set up to assist victims (personally and financially) of the attacks. The task of providing assistance to the survivors and the families of victims is ongoing.


The fires at the World Trade Center site continued to burn for three months while rescue workers removed and sifted through debris. Some debris was sent to the National Institute of Standards and Technology for analysis, including one steel beam known to have been struck by an airliner.

On January 18, 2002, the last hospitalized survivor of the World Trade Center attack was released from the hospital.

Six months after the attack, the 1.5 million tons of debris had been removed from the WTC site and work continued below ground level, despite concerns that the slurry wall around the site might collapse. Ceremonies marking the end of the debris removal took place at the end of May 2002.

About 100 tons of asbestos were used in the construction of the WTC and had not yet been fully removed [1]. The attacks released dense clouds of dust into the air of Manhattan, and samples of the residue have shown small percentages of asbestos. As the incubation period for asbestos-related diseases is up to 30 years after inhalation, some citizens living in affected areas may suffer long term effects.


Though no group has explicitly claimed responsibility, the Al-Qaida organization has praised the attacks and the organization's leaders have hinted of their involvement in the incidents (see responsibility for more). The U.S. government immediately launched a response, stating its intentions to go to war against those it assumed responsible.

Recent statements and revelations

Additional information about the planning and execution of the attacks by Al-Qaida came to light following the capture of two of its members - Khalid Shaikh Mohammed and Ramzi Binalshibh - in separate raids in 2003 and 2002, and an exclusive interview with al Jazeera journalist Yosro Fauda in September 2002.

Amongst the things that were revealed in these statements was that Khalid Mohammed was the instigator and prime organiser of the attacks. The first hijack plan that Mohammed presented to the top brass of Al-Qaida called for several airplanes on both east and west coastss to be hijacked and driven into targets. Mohammed's plan came from an earlier foiled terrorist plot called Operation Bojinka.

Osama bin Laden was aware of these plans, and used his authority to gradually scale them down to an operation with four planes.

Six of the hijackers played active parts in the planning, including the four who became the pilots. The other two were Khalid al-Mihdhar and Nawaf al-Hazmi. CIA operatives monitored these two when they made visits to the USA, but did not notify the FBI or gain any inkling of what the hijackers were up to.

The targets ultimately chosen were the World Trade Center, the Pentagon, and United States Capitol. Flight 93 was meant to crash into the lattermost. The White House was considered as a target, but was dismissed as being too hard to spot from the air. In the communications that developed as the scheme took form, the Pentagon was known as the Faculty of Arts, Capitol Hill was referred to as the Faculty of Law, and the World Trade Center was referred to as the Faculty of Town Planning.

There were early plans to have 20 hijackers, but the final list always did consist of 19 hijackers. Binalsibh was meant to be the 20th, but he was repeatedly denied entry into the US. Zacarias Moussaoui was considered for the role of the 20th hijacker, but plans to include him were never finalized, as the al-Qaeda hierarchy had doubts about his reliability.

September 17th, 2001 -- A small portion of the scene where the World Trade Center collapsed following the Sept. 11 terrorist attack.

His capture by the US authorities did, however, accelerate the plans of the hijackers. It was hijacker Mohammed Atta who notified Binalsibh after Moussaoui's capture in a coded telephone message, "two sticks, a dash, and a cake with a stick down", meaning that the fateful day would be September 11. Thus, it was Atta who chose the date.

Earlier revelations

In late September, British Prime Minister Tony Blair released information compiled by Western intelligence agencies connecting Osama bin Laden to the Afghan Taliban leadership, and Osama bin Laden's Al-Qaida organisation.

The Taliban refused to extradite Osama bin Laden and all other Al-Qaida leaders based in Afghanistan to the United States without conclusive evidence, although they proposed to extradite to an Islamic country. (Previously, the Taliban had refused to extradite Osama without conclusive evidence that he was involved in the 1998 U.S. embassy bombings in Kenya and Tanzania, and the bombing of the USS Cole in a harbor in Yemen.) The setting of that open-ended standard was treated as a refusal based on sympathy with and dependence on Al Qaida, and a coalition led by the United States launched an invasion of Afghanistan on October 7.

After the U.S. attack removed the Taliban from power in many parts of Afghanistan, a videotape was discovered abandoned in Kabul, the Afghan capital, which showed Osama discussing the attacks in language that is hard to account for except in ways that imply he intended to indicate his foreknowledge.

U.S. Investigators have nearly a decade of statements directly from Osama bin Laden that state the motives for the attacks on the US and US interests. Osama bin Laden has been interviewed by western journalists and has been video and audio taped repeating the same list of grievances as the reason he calls for attacks for years. Most of these statements have been confirmed as those from Osama but at least one hasn't, a letter, purporting to be written by Osama bin Laden, which appeared on the Internet in Arabic. It was reported in a November 24, 2002 article in The Observer, in an article that cites no intelligence-agency estimates about the likelihood of its authenticity, only using journalists' beliefs that it is really a letter from Osama explaining the motivations for the attacks.

Reasons to question the authenticity of this particular letter include

  • a style different from all the interviews
  • a strange intro to the letter that acts like the motives have not been stated before.
  • lack of any other source that includes as motives either
There have been many interviews with Osama, all of them listing specific foreign policies of the US as the reasons for attacks on the US.

In fact in an audio tape by bin Laden that addressed the false reasons the Bush Administration created:

"... the Mujahideen saw the black gang of thugs in the White House hiding the Truth, and their stupid and foolish leader, who is elected and supported by his people, denying reality and proclaiming that we (the Mujahideen) were striking them because we were jealous of them (the Americans), whereas the reality is that we are striking them because of their evil and injustice in the whole of the Islamic World, especially in Iraq and Palestine and their occupation of the Land of the Two Holy Sanctuaries. Upon seeing this, the Mujahideen decided teach them a lesson and to take the war to their heartland. On the blessed Tuesday 11 September 2001, while the Zionist-American Alliance was targeting our children and our people in the blessed land of Al-Aqsa, with American tanks and planes in the hands of the Jews, and our people in Iraq were suffering from the America's sanctions upon them, and the Islamic world was very far away from establishing Islam properly." -Osama Bin Laden, February 14, 2003

In the paragraph before that he again recaps the motives that he has mentioned for years:

" ... in 1995, the explosion in Riyadh took place, killing four Americans, in a clear message from the people of that region displaying their rejection and opposition to the American policy of bankrolling the Jews and occupying the Land of the Two Holy Sanctuaries. The following year, another explosion in Al-Khobar killed 19 Americans and wounded more than 400 of them, prompting them to move their bases from the cities to the desert. Then in 1998, the Mujahideen warned America to cease their support to the Jews and to leave the Land of the Two Holy Sanctuaries, but the enemy refused to heed this warning, so the Mujahideen, with the ability from Allah, smashed them with two mighty smashes in East Africa. Then again America was warned, but she refused to pay attention to the warnings, so the Mujahideen destroyed the American Destroyer, the USS Cole, in Aden, in a martyrdom operation, striking a solid blow to the face of the American military and at the same time, exposing the Yemeni Government as American agents, similar to all the countries in the region." -Osama bin Laden February 14, 2003

For many years Osama has made clear what the motives are:

Osama bin Laden said in an interview in 1999, "The International Islamic Front for Jihad against the U.S. and Israel has issued a crystal-clear fatwa calling on the Islamic nation to carry on jihad aimed at liberating holy sites. The nation of Muhammad has responded to this appeal. If the instigation for jihad against the Jews and the Americans in order to liberate Al-Aksa Mosque and the Holy Ka'aba Islamic shrines in the Middle East is considered a crime, then let history be a witness that I am a criminal."

"We swore that America wouldn't live in security until we live it truly in Palestine. This showed the reality of America, which puts Israel's interest above its own people's interest. America won't get out of this crisis until it gets out of the Arabian Peninsula, and until it stops its support of Israel." -Osama bin Laden, October 2001

"The Pile", Manhattan

A German friend of Mohammed Atta is quoted as describing him as "most imbued actually about Israeli politics in the region and about US protection of these Israeli politics in the region. And he was to a degree personally suffering from that."

The FBI testified clearly that Al-Qaeda had specific goals. "One of the primary goals of Sunni extremists is the removal of U.S. military forces from the Persian Gulf area, most notably Saudi Arabia."

Terrorism expert Richard E. Rubenstein writes that Bin Laden has made clear in previous remarks that he is seeking to force a U.S. withdrawal from the Arabian peninsula.

The shoe bomber (Richard Reid) has said:"The reason for me sending you (a document he calls his "will") is so you can see that I didn't do this act out of ignorance nor did I just do it because I want to die, but rather because I see it as a duty upon me to help remove the oppressive American forces from the Muslim land and that this is the only way for us to do so as we do not have other means to fight them."

These facts point to a motive for attacking the WTC in 2001 that is consistent with the motive expressed by terrorists in a letter sent to the New York Times after the 1993 bombing attack of the WTC, "We declare our responsibility for the explosion on the mentioned building. This action was done in response for the American political, economical, and military support to Israel the state of terrorism and to the rest of the dictator countries in the region." It is also the same motive that Mir Aimal Kasi had for killing CIA employees Frank Darling and Lansing Bennett outside CIA headquarters in Langley, Virginia in 1993. Mir Aimal Kasi said, "What I did was a retaliation against the US government for American policy in the Middle East and its support of Israel."

The Bush Administration and others have insisted the terrorists are motivated to attack by "hatred of America". President Bush claimed, "America was targeted for attack because we're the brightest beacon for freedom and opportunity in the world." The purported statements of bin Laden in the disputed letter surely intend to include "depravity of Western civilization" as a motive for attacks. But even this letter says that the motive for attacking is because they have been wronged. It starts with a quote talking about them being wronged: "Permission to fight (against disbelievers) is given to those (believers) who are fought against, because they have been wronged and surely, Allah is Able to give them (believers) victory" Quran 22:39 It doesn't state that they attack because of "hating our freedoms." The letter also states, "Why are we fighting and opposing you? The answer is very simple: (1) Because you attacked us and continue to attack us." Yet the letter then goes on the points never raised in anything that has actaully been verified as coming from Osama bin Laden and seems to be created to distort the clear record of years of statements from Osama.

Following the attack, the United States government has been on heightened alert for new attacks, repeatedly warning of "imminent attacks".


A joint Congressional committee concluded its investigation in July 2003. While the events show inadequacies in some parts of the United States government, in terms of both the way the attacks may have been prevented with better use and gathering of intelligence and in the way that defense forces reacted to the attacks, not a single public official was removed from office.

As well as the invasion of Afghanistan, claims of a strong link between bin Laden and Saddam Hussein, and the argument that the attack demonstrated the need to preemptively strike at forces hostile to US and western interests, were used by the US Administration as justification for the 2003 invasion of Iraq, though such links were hotly questioned at the time and little evidence of such links has since emerged.

In May 2003, a ten-member group was formed, the National Commission on Terrorist Attacks Upon the United States. Among other requests, the Commission requested information from the Federal Aviation Administration on air traffic control tracking of hijacked aircraft and the FAA's communication with NORAD. By October, the information had not been handed over, provoking the Commission to subpoena the FAA for the information and accuse it of slowing the probe. On November 7, the Commission subpoenaed the military's North American Aerospace Defense Command records for information NORAD promised but never deliver. The Commission also threatened to subpoena the White House if information regarding intelligence reports given to the president was not turned over.

List of topics

External links