The September 11 attacks were a series of four coordinated terrorist attacks by the Islamic terrorist group al-Qaeda against the United States on the morning of Tuesday, September 11, 2001. The attacks killed 2,977 people, injured over 6,000 others, and caused at least $10 billion in infrastructure and property damage. Additional people have died of 9/11-related cancer and respiratory diseases in the months and years following the attacks.
Four passenger airliners operated by two major U.S. passenger air carriers —all of which departed from airports in northeastern United States bound for San Francisco and Los Angeles—were hijacked by 19 al-Qaeda terrorists. Two of the planes, American Airlines Flight 11 and United Airlines Flight 175, were crashed into the North and South towers, respectively, of the World Trade Center complex in Lower Manhattan. Within an hour and 42 minutes, both 110-story towers collapsed. Debris and the resulting fires caused a partial or complete collapse of all other buildings in the World Trade Center complex, including the 47-story 7 World Trade Center tower, as well as significant damage to ten other large surrounding structures. A third plane, American Airlines Flight 77, was crashed into the Pentagon in Arlington County, Virginia, which led to a partial collapse of the building's west side. The fourth plane, United Airlines Flight 93, was initially flown toward Washington, D.C., but crashed into a field in Stonycreek Township near Shanksville, Pennsylvania, after its passengers thwarted the hijackers. 9/11 is the single deadliest terrorist attack in human history and the single deadliest incident for firefighters and law enforcement officers in the history of the United States, with 343 and 72 killed, respectively.
Suspicion quickly fell on al-Qaeda. The United States responded by launching the War on Terror and invading Afghanistan to depose the Taliban, which had failed to comply with U.S. demands to extradite Osama bin Laden and expel al-Qaeda from Afghanistan. Many countries strengthened their anti-terrorism legislation and expanded the powers of law enforcement and intelligence agencies to prevent terrorist attacks. Although Osama bin Laden, al-Qaeda's leader, initially denied any involvement, in 2004 he claimed responsibility for the attacks. Al-Qaeda and bin Laden cited U.S. support of Israel, the presence of U.S. troops in Saudi Arabia, and sanctions against Iraq as motives. After evading capture for almost a decade, bin Laden was located in Pakistan and killed by SEAL Team Six of the U.S. Navy in May 2011.
The destruction of the World Trade Center and nearby infrastructure seriously harmed the economy of Lower Manhattan and had a significant effect on global markets, which resulted in the closing of Wall Street until September 17 and the civilian airspace in the U.S. and Canada until September 13. Many closings, evacuations, and cancellations followed, out of respect or fear of further attacks. Cleanup of the World Trade Center site was completed in May 2002, and the Pentagon was repaired within a year. On November 18, 2006, construction of One World Trade Center began at the World Trade Center site. The building opened on November 3, 2014. Numerous memorials have been constructed, including the National September 11 Memorial & Museum in New York City, the Pentagon Memorial in Arlington County, Virginia, and the Flight 93 National Memorial in a field in Stonycreek Township near Shanksville, Pennsylvania.
Although not confirmed, there is evidence of alleged Saudi Arabian involvement in the attacks. Given as main evidence in these charges are the contents of the 28 redacted pages of the December 2002 Joint Inquiry into Intelligence Community Activities before and after the Terrorist Attacks of September 11, 2001, conducted by the Senate Select Committee on Intelligence and the House Permanent Select Committee on Intelligence. These 28 pages contain information regarding the material and financial assistance given to the hijackers and their affiliates leading up to the attacks by the Saudi Arabian government.
As a consequence of the attacks, the United States has been in a state of national emergency ever since 2001.
Background
Al-Qaeda
The origins of al-Qaeda can be traced to 1979 when the Soviet Union invaded Afghanistan. Osama bin Laden traveled to Afghanistan and helped organize Arab mujahideen to resist the Soviets. Under the guidance of Ayman al-Zawahiri, bin Laden became more radical. In 1996, bin Laden issued his first fatwā, calling for American soldiers to leave Saudi Arabia.
In a second fatwā in 1998, bin Laden outlined his objections to American foreign policy with respect to Israel, as well as the continued presence of American troops in Saudi Arabia after the Gulf War. Bin Laden used Islamic texts to exhort Muslims to attack Americans until the stated grievances are reversed. Muslim legal scholars 'have throughout Islamic history unanimously agreed that the jihad is an individual duty if the enemy destroys the Muslim countries', according to bin Laden. Al Jazeera broadcast a statement by bin Laden on September 16, 2001, stating, '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 is seen talking to Khaled al-Harbi and admits foreknowledge of the attacks. On December 27, 2001, a second bin Laden video was released. In the video, he said: but he stopped short of admitting responsibility for the attacks. The transcript refers several times to the United States specifically targeting Muslims.
Shortly before the U.S. presidential election in 2004, bin Laden used a taped statement to publicly acknowledge al-Qaeda's involvement in the attacks on the United States. He admitted his direct link to the attacks and said they were carried out because:
Bin Laden said he had personally directed his followers to attack the World Trade Center and the Pentagon. Another video obtained by Al Jazeera in September 2006 shows bin Laden with Ramzi bin al-Shibh, as well as two hijackers, Hamza al-Ghamdi and Wail al-Shehri, as they make preparations for the attacks. The U.S. never formally indicted bin Laden for the 9/11 attacks, but he was on the FBI's Most Wanted List for the bombings of the U.S. Embassies in Dar es Salaam, Tanzania, and Nairobi, Kenya. After a 10-year manhunt, bin Laden was killed by American special forces in a compound in Abbottabad, Pakistan, on May 2, 2011.
Khalid Sheikh Mohammed
Journalist Yosri Fouda of the Arabic television channel Al Jazeera reported that in April 2002 Khalid Sheikh Mohammed admitted his involvement in the attacks, along with Ramzi bin al-Shibh. 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.
Mohammed was arrested on March 1, 2003, in Rawalpindi, Pakistan, by Pakistani security officials working with the CIA. He was then held at multiple CIA secret prisons and Guantanamo Bay where he was interrogated and tortured with methods including waterboarding. During U.S. hearings at Guantanamo Bay in March 2007, Mohammed again confessed his responsibility for the attacks, stating he 'was responsible for the 9/11 operation from A to Z' and that his statement was not made under duress.
A letter presented by the lawyers of Khaled Sheikh Mohammed in the U.S. District Court, Manhattan on 26 July 2019, indicated that the prime accused mastermind was interested in testifying against Saudi Arabia’s role in the 9/11 attacks and helping the victims and families of the victims of 9/11. However, as per the letter, Mohammed's agreement upon the same in “the present time” isn't certain. James Kreindler, one of the lawyers for the plaintiff also raised question over the usefulness of Mohammed.
Other al-Qaeda members
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. To date, only peripheral figures have been tried or convicted for the attacks.
On September 26, 2005, the Spanish high court sentenced Abu Dahdah to 27 years in prison for conspiracy on the 9/11 attacks and being a member of the terrorist organization al-Qaeda. At the same time, another 17 al-Qaeda members were sentenced to penalties of between six and eleven years. On February 16, 2006, the Spanish Supreme Court reduced the Abu Dahdah penalty to 12 years because it considered that his participation in the conspiracy was not proven.
Also in 2006, Moussaoui—who some originally suspected might have been the assigned 20th hijacker—was convicted for the lesser role of conspiracy to commit acts of terrorism and air piracy. He was sentenced to life in prison without parole in the United States. Mounir el-Motassadeq, an associate of the Hamburg-based hijackers, served 15 years in Germany for his role in helping the hijackers prepare for the attacks. He was released in October 2018, and deported to Morocco.
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.