September 11 Attacks

The September 11 attacks, commonly known as 9/11, were four coordinated Islamist suicide terrorist attacks carried out by al-Qaeda against the United States in 2001. That morning, 19 terrorists hijacked four commercial airliners scheduled to travel from the New England and Mid-Atlantic regions of the East Coast to California. The hijackers crashed the first two planes into the Twin Towers of the World Trade Center in New York City, two of the world's five tallest buildings at the time, and aimed the next two flights toward targets in or near Washington, D.C., in an attack on the nation's capital. The third team succeeded in crashing into The Pentagon, the headquarters of the U.S. Department of Defense in Arlington County, Virginia, while the fourth plane crashed in rural Pennsylvania following a passenger revolt. The attacks killed nearly 3,000 people and instigated the multi-decade global war on terror.

The first impact was that of American Airlines Flight 11, which crashed into the North Tower of the World Trade Center complex in Lower Manhattan at 8:46 a.m. Sixteen minutes later, at 9:03, the World Trade Center's South Tower was hit by United Airlines Flight 175. Both 110-story skyscrapers collapsed within an hour and forty-one minutes, bringing about the destruction of the remaining five structures in the WTC complex and several other nearby buildings. A third flight, American Airlines Flight 77, crashed into The Pentagon at 9:37 a.m., causing a partial collapse. The fourth and final flight, United Airlines Flight 93, flew in the direction of the capital. Alerted to the previous attacks, the passengers retaliated in an attempt to take control of the aircraft, forcing the hijackers to crash the plane in a Stonycreek Township field, near Indian Lake and Shanksville, at 10:03 a.m. Investigators determined that Flight 93's target was either the United States Capitol or the White House.

Within hours of the attacks, the Central Intelligence Agency had determined that al-Qaeda was responsible. The United States formally responded by launching the war on terror and invading Afghanistan to depose the Taliban, which rejected the conditions of U.S. terms to expel al-Qaeda from Afghanistan and extradite its leaders. The U.S.'s invocation of Article 5 of the North Atlantic Treaty—its only usage to date—called upon allies to fight al-Qaeda. As U.S. and NATO invasion forces swept through Afghanistan, al-Qaeda leader Osama bin Laden disappeared into the White Mountains, eluding captivity by Western forces. Although bin Laden initially denied any involvement, in 2004 he formally claimed responsibility for the attacks. Al-Qaeda's cited motivations included U.S. support of Israel, the presence of U.S. military bases in Saudi Arabia and sanctions against Iraq. The nearly decade-long manhunt for bin Laden concluded on May 2, 2011, when he was killed during a U.S. military raid after being tracked down to his compound in Abbottabad, Pakistan. The war in Afghanistan continued for another eight years until the agreement was made in February 2020 for American and NATO troops to withdraw from the country, and the last members of the U.S. armed forces left the region on August 30, 2021, resulting in the return to power of the Taliban.

Not including the hijackers, the attacks killed 2,977 people, injured thousands more and gave rise to substantial long-term health consequences while also causing at least $10 billion in infrastructure and property damage. It remains the deadliest terrorist act in human history as well as the single deadliest incident for both firefighters and law enforcement personnel in the history of the United States, causing the deaths of 343 and 72 members respectively. The loss of life stemming from the impact of Flight 11 secured its place as the most lethal plane crash in aviation history followed by the death toll incurred by Flight 175. The destruction of the World Trade Center and its environs seriously harmed the U.S. economy and induced global market shocks. Many other countries strengthened anti-terrorism legislation and expanded their powers of law enforcement and intelligence agencies. Cleanup of the World Trade Center site (colloquially "Ground Zero") took eight months and was completed in May 2002, while The Pentagon was repaired within a year. After delays in the design of a replacement complex, construction of the One World Trade Center began in November 2006; it opened in November 2014. Memorials to the attacks include the National September 11 Memorial & Museum in New York City, The Pentagon Memorial in Arlington County, Virginia, and the Flight 93 National Memorial at the Pennsylvania crash site.

Background

Al-Qaeda

The origins of al-Qaeda can be traced to 1979, when the Soviet Union invaded Afghanistan. Soon after the invasion, Osama bin Laden traveled to Afghanistan and helped organize Arab mujahideen (the "Afghan Arabs") to resist the "Communist invaders" (Soviets) until their exit from the country in 1989. During that time, bin Laden, together with Abdullah Azzam, formed the Maktab al-Khidamat (MAK) in 1984, an organization to support Arab mujahideen who came to join the jihad in Afghanistan.

The U.S. Central Intelligence Agency (CIA) funneled several billion dollars worth of weapons to the indigenous Afghan mujahideen resistance, a portion of which bled to the Arab volunteers. However, no direct evidence of U.S. aid to bin Laden or any of his affiliates was ever uncovered.

In 1996, bin Laden issued his first fatwā, calling for American soldiers to leave Saudi Arabia. In a second 1998 fatwā, bin Laden outlined his objections to American foreign policy with respect to the State of Israel, as well as the continued presence of American troops in Saudi Arabia after the Gulf War. A subscriber to the Athari (literalist) and Wahhabi school of Islamic theology, Bin Laden used Islamic Quran texts to exhort Muslims to attack Americans until the stated grievances were reversed. According to bin Laden, Muslim legal scholars had "throughout Islamic history unanimously agreed that the jihad is an individual duty if the enemy destroys the Muslim countries".

The Hamburg cell in Germany included radical Islamists who eventually came to be key operatives in the 9/11 attacks. Mohamed Atta; Marwan al-Shehhi; Ziad Jarrah; Ramzi bin al-Shibh; and Said Bahaji were all members of al-Qaeda's Hamburg cell.

Osama bin Laden

Bin Laden orchestrated the attacks. He initially denied involvement, but later recanted his false statements. Al Jazeera broadcast a statement by him on September 16, 2001: "I stress that I have not carried out this act, which appears to have been carried out by individuals with their own motivation". In November 2001, U.S. forces recovered a videotape from a destroyed house in Jalalabad, Afghanistan. In the video, bin Laden, talking to Khaled al-Harbi, admitted foreknowledge of the attacks. On December 27, 2001, a second video of bin Laden was released in which he, stopping short of admitting responsibility for the attacks, said:

It has become clear that the West in general and America in particular have an unspeakable hatred for Islam. ... It is the hatred of crusaders. Terrorism against America deserves to be praised because it was a response to injustice, aimed at forcing America to stop its support for Israel, which kills our people. ... We say that the end of the United States is imminent, whether Bin Laden or his followers are alive or dead, for the awakening of the Muslim ummah [nation] has occurred. ... It is important to hit the economy (of the United States), which is the base of its military power...If the economy is hit they will become reoccupied. — 

Shortly before the 2004 U.S. presidential election, bin Laden used a taped statement to publicly acknowledge al-Qaeda's involvement in the attacks. He admitted his direct link to the attacks and said they were carried out because:

The events that affected my soul in a direct way started in 1982 when America permitted the Israelis to invade Lebanon and the American Sixth Fleet helped them in that. This bombardment began and many were killed and injured and others were terrorised and displaced.

I couldn't forget those moving scenes, blood and severed limbs, women and children sprawled everywhere. Houses destroyed along with their occupants and high rises demolished over their residents, rockets raining down on our home without mercy...And as I looked at those demolished towers in Lebanon, it entered my mind that we should punish the oppressor in kind and that we should destroy towers in America in order that they taste some of what we tasted and so that they be deterred from killing our women and children.

And that day, it was confirmed to me that oppression and the intentional killing of innocent women and children is a deliberate American policy. Destruction is freedom and democracy, while resistance is terrorism and intolerance.

Bin Laden said that he had personally directed his followers to attack the World Trade Center and The Pentagon. Another video obtained by Al Jazeera in September 2006 showed bin Laden with one of the attacks' chief planners, Ramzi bin al-Shibh, as well as hijackers, Hamza al-Ghamdi and Wail al-Shehri, amidst making preparations for the attacks. Bin Laden had been on the FBI's Most Wanted List since 1998 for the 1998 bombings of the U.S. embassies in Tanzania and Kenya.

Khalid Sheikh Mohammed and other al-Qaeda members

Journalist Yosri Fouda of the Arabic television channel Al Jazeera reported that in April 2002 al-Qaeda member Khalid Sheikh Mohammed admitted his involvement in the attacks, along with Ramzi bin al-Shibh. The 2004 9/11 Commission Report determined that the animosity towards the United States felt by Mohammed, the principal architect of the 9/11 attacks, stemmed from his "violent disagreement with U.S. foreign policy favoring Israel". Mohammed was also an adviser and financier of the 1993 World Trade Center bombing and the uncle of Ramzi Yousef, the lead bomber in that attack. In late 1994, Mohammed and Yousef moved on to plan a new terrorist attack called the Bojinka plot planned for January 1995. Despite a failure and Yousef's capture by U.S. forces the following month, the Bojinka plot would highly influence the later 9/11 attacks.

In "Substitution for Testimony of Khalid Sheikh Mohammed" from the trial of Zacarias Moussaoui, five people are identified as having been completely aware of the operation's details. They are bin Laden; Khalid Sheikh Mohammed; Ramzi bin al-Shibh; Abu Turab al-Urduni; and Mohammed Atef.

Motives

Osama bin Laden's declaration of a holy war against the United States, and a 1998 fatwā signed by bin Laden and others, calling for the killing of Americans, are seen by investigators as evidence of his motivation.

In bin Laden's November 2002 "Letter to America", he explicitly stated that al-Qaeda's motives for the attacks included:

• U.S. support of Israel
• The "attacks against Muslims" in Somalia
• Support of the Philippines against Muslims in the Moro conflict
• Support for Israeli "aggression" against Muslims in Lebanon
• Support of Russian "atrocities against Muslims" in Chechnya
• Pro-American governments in the Middle East (who "act as your agents") being against Muslim interests
• Support of Indian "oppression against Muslims" in Kashmir
• The presence of U.S. troops in Saudi Arabia
• The sanctions against Iraq
• Environmental destruction After the attacks, bin Laden and Ayman al-Zawahiri released additional videotapes and audio recordings, some of which repeated those reasons for the attacks. Two particularly important publications were bin Laden's 2002 "Letter to America" and a 2004 videotape by bin Laden. Bin Laden interpreted Muhammad as having banned the "permanent presence of infidels in Arabia". In 1996, bin Laden issued a fatwā calling for American troops to leave Saudi Arabia. In 1998, al-Qaeda wrote "for over seven years the United States has been occupying the lands of Islam in the holiest of places, the Arabian Peninsula, plundering its riches, dictating to its rulers, humiliating its people, terrorizing its neighbors, and turning its bases in the Peninsula into a spearhead through which to fight the neighboring Muslim peoples". In a December 1999 interview, bin Laden said he felt that Americans were "too near to Mecca", and considered this a provocation to the entire Muslim world. One analysis of suicide terrorism suggested that without U.S. troops in Saudi Arabia, al-Qaeda likely would not have been able to get people to commit to suicide missions. In the 1998 fatwā, al-Qaeda identified the Iraq sanctions as a reason to kill Americans, condemning the "protracted blockade" among other actions that constitute a declaration of war against "Allah, his messenger, and Muslims". The fatwā declared that "the ruling to kill the Americans and their allies – civilians and military – is an individual duty for every Muslim who can do it in any country in which it is possible to do it, in order to liberate the al-Aqsa Mosque and the holy mosque of Mecca from their grip, and in order for their [the Americans'] armies to move out of all the lands of Islam, defeated and unable to threaten any Muslim". In 2004, Bin Laden claimed that the idea of destroying the towers had first occurred to him in 1982, when he witnessed Israel's bombardment of high-rise apartment buildings during the 1982 Lebanon War. Some analysts, including political scientists John Mearsheimer and Stephen Walt, also claimed that U.S. support of Israel was one motive for the attacks. In 2004 and 2010, bin Laden again connected the September 11 attacks with U.S. support of Israel, although most of the letter expressed bin Laden's disdain for President Bush and bin Laden's hope to "destroy and bankrupt" the U.S. Other motives have been suggested in addition to those stated by bin Laden and al-Qaeda. Some authors suggested the "humiliation" that resulted from the Islamic world falling behind the Western world – this discrepancy was rendered especially visible by globalization and a desire to provoke the U.S. into a broader war against the Islamic world in the hope of motivating more allies to support al-Qaeda. Similarly, others have argued that 9/11 was a strategic move with the objective of provoking America into a war that would incite a pan-Islamic revolution. Documents seized during the 2011 operation that killed bin Laden included a few notes handwritten by bin Laden in September 2002 with the heading "The Birth of the Idea of September 11". In these notes he describes how he was inspired by the crash of EgyptAir Flight 990 on October 31, 1999, which was deliberately crashed by co-pilot Gameel Al-Batouti. "This is how the idea of 9/11 was conceived and developed in my head, and that is when we began the planning" bin Laden continued, adding that no one but Abu Hafs and Abu al-Khair knew about it at the time. The 9/11 Commission Report identified Khalid Sheikh Mohammed as the architect of 9/11, but he is not mentioned in bin Laden's notes.