September 11 attacks

The September 11 attacks (often referred to as September 11th or 9/11) were a series of coordinated suicide attacks by Al-Qaeda upon the United States on September 11, 2001. On that morning, 19 Al-Qaeda terrorists hijacked four commercial passenger jet airliners. The hijackers intentionally crashed two of the airliners into the Twin Towers of the World Trade Center in New York City, killing everyone on board and many others working in the buildings. Both buildings collapsed within two hours, destroying nearby buildings and damaging others. The hijackers crashed a third airliner into the Pentagon in Arlington, Virginia, just outside of Washington, D.C. The fourth plane crashed into a field near Shanksville in rural Pennsylvania, after some of its passengers and flight crew attempted to retake control of the plane, which the hijackers had redirected toward Washington, D.C. There were no survivors from any of the flights.

In total 2,993 people, including the hijackers, died in the attacks. The overwhelming majority of casualties were civilians, including nationals of over 90 countries. In addition, the death of at least one person from lung disease was ruled by a medical examiner to be a result of exposure to dust from the World Trade Center's collapse.

The United States responded to the attacks by launching a "War on Terrorism", invading Afghanistan to depose the Taliban, who had harbored al-Qaeda terrorists, and enacting the USA PATRIOT Act. Many other countries also strengthened their anti-terrorism legislation and expanded law enforcement powers. Some American stock exchanges stayed closed for the rest of the week following the attack, and posted enormous losses upon reopening, especially in the airline and insurance industries. The destruction of billions of dollars worth of office space caused serious damage to the economy of Lower Manhattan.

The damage to the Pentagon was cleared and repaired within a year, and the Pentagon Memorial was built on the site. The rebuilding process has started on the World Trade Center site. In 2006 a new office tower was completed on the site of 7 World Trade Center. The 1 World Trade Center is currently under construction at the site and, at 1,776 ft (541 m) upon completion in 2011, it will become one of the tallest buildings in North America. Three more towers were originally expected to be built between 2007 and 2012 on the site.

Attacks
Early on the morning on September 11, 2001, nineteen hijackers took control of four commercial airliners en route to San Francisco and Los Angeles from Boston, Newark, and Washington, D.C. (Washington Dulles International Airport). At 8:46 a.m., American Airlines Flight 11 was crashed into the World Trade Center's North Tower, followed by United Airlines Flight 175 which hit the South Tower at 9:03 a.m. Another group of hijackers flew American Airlines Flight 77 into the Pentagon at 9:37 a.m. A fourth flight, United Airlines Flight 93 crashed near Shanksville, Pennsylvania at 10:03 a.m, after the passengers on board engaged in a fight with the hijackers. Its ultimate target was thought to be either the United States Capitol or White House.

During the hijacking of the airplanes, the hijackers used weapons to stab and/or kill aircraft pilots, flight attendants and passengers. Reports from phone callers from the planes indicated that knives were used by the hijackers to stab attendants and in at least one case, a passenger, during two of the hijackings.

Some passengers were able to make phone calls using the cabin airphone service and mobile phones, and provide details, including that several hijackers were aboard each plane, that mace or other form of noxious chemical spray, such as tear gas or pepper spray was used, and that some people aboard had been stabbed.

The 9/11 Commission established that two of the hijackers had recently purchased Leatherman multi-function hand tools. A flight attendant on Flight 11, a passenger on Flight 175, and passengers on Flight 93 mentioned that the hijackers had bombs, but one of the passengers also mentioned he thought the bombs were fake. No traces of explosives were found at the crash sites, and the 9/11 Commission believed the bombs were probably fake.

On United Airlines Flight 93, black box recordings revealed that crew and passengers attempted to seize control of the plane from the hijackers after learning through phone calls that similarly hijacked planes had been crashed into buildings that morning. According to the transcript of Flight 93's recorder, one of the hijackers gave the order to roll the plane once it became evident that they would lose control of the plane to the passengers. Soon afterward, the aircraft crashed into a field near Shanksville in Stonycreek Township, Somerset County, Pennsylvania, at 10:03:11 a.m. local time (14:03:11 UTC). Khalid Sheikh Mohammed, organiser of the attacks, mentioned in a 2002 interview with Yosri Fouda, an al Jazeera journalist, that Flight 93's target was the United States Capitol, which was given the code name "the Faculty of Law".

Three buildings in the World Trade Center Complex collapsed due to structural failure on the day of the attack. The south tower (2 WTC) fell at approximately 9:59 a.m., after burning for 56 minutes in a fire caused by the impact of United Airlines Flight 175. The north tower (1 WTC) collapsed at 10:28 a.m., after burning for approximately 102 minutes. When the north tower collapsed, debris heavily damaged the nearby 7 World Trade Center (7 WTC) building. Its structural integrity was further compromised by fires, and the building collapsed later in the day at 5:20 p.m.

The attacks created widespread confusion among news organizations and air traffic controllers across the United States. All international civilian air traffic was banned from landing on US soil for three days. Aircraft already in flight were either turned back or redirected to airports in Canada or Mexico. News sources aired unconfirmed and often contradictory reports throughout the day. One of the most prevalent of these reported that a car bomb had been detonated at the U.S. State Department's headquarters in Washington, D.C. Soon after reporting for the first time on the Pentagon crash, CNN and other media also briefly reported that a fire had broken out on the Washington Mall. Another report went out on the AP wire, claiming that a Delta Air Lines airliner—Flight 1989—had been hijacked. This report, too, turned out to be in error; the plane was briefly thought to represent a hijack risk, but it responded to controllers and landed safely in Cleveland, Ohio.

Casualties
There were a total of 2,995 deaths, including the 19 hijackers and 2,976 victims. The victims were distributed as follows: 246 on the four planes (from which there were no survivors), 2,605 in New York City in the towers and on the ground, and 125 at the Pentagon. All the deaths in the attacks were civilians except for 55 military personnel killed at the Pentagon.

More than 90 countries lost citizens in the attacks on the World Trade Center. In 2007, the New York City medical examiner's office added Felicia Dunn-Jones to the official death toll from the September 11 attacks. Dunn-Jones died five months after 9/11 from a lung condition which was linked to exposure to dust during the collapse of the World Trade Center. Leon Heyward, who died of lymphoma in 2008, was added to the official death toll in 2009.

NIST estimated that about 17,400 civilians were in the World Trade Center complex at the time of the attacks, while turnstile counts from the Port Authority suggest that 14,154 people were typically in the Twin Towers by 8:45 a.m. The vast majority of people below the impact zone safely evacuated the buildings, along with 18 people who were in the impact zone in the south tower and a number above the impact zone who evidently used the one intact stairwell in the south tower. At least 1,366 people died who were at or above the floors of impact in the North Tower and at least 618 in the South Tower, where evacuation had begun before the second impact. Thus over 90% of the workers and visitors who died in the Towers had been at or above impact.

According to the Commission Report, hundreds were killed instantly by the impact, while the rest were trapped and died after tower collapse. At least 200 people jumped to their deaths from the burning towers (as depicted in the photograph "The Falling Man"), landing on the streets and rooftops of adjacent buildings hundreds of feet below. Some of the occupants of each tower above its point of impact made their way upward toward the roof in hope of helicopter rescue, but the roof access doors were locked. No plan existed for helicopter rescues, and on September 11, the thick smoke and intense heat would have prevented helicopters from conducting rescues.

A total of 411 emergency workers who responded to the scene died as they attempted to rescue people and fight fires. The New York City Fire Department (FDNY) lost 341 firefighters and 2 FDNY paramedics. The New York City Police Department lost 23 officers. The Port Authority Police Department lost 37 officers, and 8 additional EMTs and paramedics from private EMS units were killed.

Cantor Fitzgerald L.P., an investment bank on the 101st–105th floors of One World Trade Center, lost 658 employees, considerably more than any other employer. Marsh Inc., located immediately below Cantor Fitzgerald on floors 93–101 (the location of Flight 11's impact), lost 355 employees, and 175 employees of Aon Corporation were killed. After New York, New Jersey was the hardest hit state, with the city of Hoboken sustaining the most deaths.

Weeks after the attack, the estimated death toll was over 6,000. The city was only able to identify remains for about 1,600 of the victims at the World Trade Center. The medical examiner's office also collected "about 10,000 unidentified bone and tissue fragments that cannot be matched to the list of the dead". Bone fragments were still being found in 2006 as workers were preparing to demolish the damaged Deutsche Bank Building.

Damage
Along with the 110-floor Twin Towers of the World Trade Center itself, numerous other buildings at the World Trade Center site were destroyed or badly damaged, including 7 World Trade Center, 6 World Trade Center, 5 World Trade Center, 4 World Trade Center, the Marriott World Trade Center (3 WTC), and the World Financial Center complex and St. Nicholas Greek Orthodox Church.

The Deutsche Bank Building across Liberty Street from the World Trade Center complex was later condemned due to the uninhabitable, toxic conditions inside the office tower, and is undergoing deconstruction. The Borough of Manhattan Community College's Fiterman Hall at 30 West Broadway was also condemned due to extensive damage in the attacks, and is slated for deconstruction.

Other neighboring buildings including 90 West Street and the Verizon Building suffered major damage, but have since been restored. World Financial Center buildings, One Liberty Plaza, the Millenium Hilton, and 90 Church Street had moderate damage. They have since been restored. Communications equipment on top of the North Tower, including broadcast radio, television and two-way radio antenna towers, was also destroyed, but media stations were quickly able to reroute signals and resume broadcasts. In Arlington County, a portion of the Pentagon was severely damaged by fire and one section of the building collapsed.

Rescue and recovery
The Fire Department of New York City (FDNY) quickly deployed 200 units (half of the department) to the site, whose efforts were supplemented by numerous off-duty firefighters and EMTs. The New York Police Department (NYPD) sent Emergency Service Units (ESU) and other police personnel, along with deploying its aviation unit. Once on the scene, the FDNY, NYPD, and Port Authority police did not coordinate efforts, and ended up performing redundant searches for civilians.

As conditions deteriorated, the NYPD aviation unit relayed information to police commanders, who issued orders for its personnel to evacuate the towers; most NYPD officers were able to safely evacuate before the buildings collapsed. With separate command posts set up and incompatible radio communications between the agencies, warnings were not passed along to FDNY commanders.

After the first tower collapsed, FDNY commanders did issue evacuation warnings, however, due to technical difficulties with malfunctioning radio repeater systems, many firefighters never heard the evacuation orders. 9-1-1 dispatchers also received information from callers that was not passed along to commanders on the scene. Within hours of the attack, a substantial search and rescue operation was launched. After months of around-the-clock operations, the World Trade Center site was cleared by the end of May 2002.

Attackers and their motivation
Within hours of the attacks, the FBI was able to determine the names and in many cases the personal details of the suspected pilots and hijackers. Mohamed Atta's luggage, which did not make the connection from his Portland flight onto Flight 11, contained papers that revealed the identity of all 19 hijackers (all men), and other important clues about their plans, motives, and backgrounds. On the day of the attacks, the National Security Agency intercepted communications that pointed to Osama bin Laden, as did German intelligence agencies.

On September 27, 2001, the FBI released photos of the 19 hijackers, along with information about the possible nationalities and aliases of many. Fifteen of the hijackers were from Saudi Arabia, two from the United Arab Emirates, one from Egypt, and one from Lebanon. Mohamed Atta was the ringleader of the 19 hijackers. According to Jerrold Post, a professor of psychology at George Washington University and former CIA officer, the hijackers were well-educated, mature adults, whose belief systems were fully formed.

The FBI investigation into the attacks, code named operation PENTTBOM, was the largest and most complex investigation in the history of the FBI, involving over 7,000 special agents. The United States government determined that al-Qaeda, headed by Osama bin Laden, bore responsibility for the attacks, with the FBI stating "evidence linking al-Qaeda and bin Laden to the attacks of September 11 is clear and irrefutable". The Government of the United Kingdom reached the same conclusion regarding al-Qaeda and Osama bin Laden's culpability for the 11 September attacks.

Author Laurie Mylroie writing in the conservative political magazine The American Spectator in 2006 argues that Khalid Sheikh Mohammed and his family are the primary architects of 9/11 and similar attacks, and that Khalid Sheikh Mohammed's association with Osama bin Laden is secondary and that Al-Qaeda's claim of responsibility for the attack is after the fact and opportunistic. In an opposing point of view, former CIA officer Robert Baer, writing in Time magazine in 2007, asserts that George W. Bush Administration's publicizing of Khalid Sheikh Mohammed's claims of responsibility for 9/11 and numerous other acts was a mendacious attempt to claim that all of the significant actors in 9/11 had been caught.

Al-Qaeda
The origins of al-Qaeda can be traced back to 1979 when the Soviet Union invaded Afghanistan. Soon after the invasion, Osama bin Laden traveled to Afghanistan where he helped organize Arab mujahideen and established the Maktab al-Khidamat (MAK) organization to resist the Soviets. In 1989, as the Soviets withdrew, MAK was transformed into a "rapid reaction force" in jihad against governments across the Muslim world. Under the guidance of Ayman al-Zawahiri, Osama bin Laden became more radical. In 1996, bin Laden issued his first fatwā, which called for American soldiers to leave Saudi Arabia.

In a second fatwā issued in 1998, bin Laden outlined his objections to American foreign policy towards Israel, as well as the continued presence of American troops in Saudi Arabia after the Gulf War. Bin Laden used Islamic texts to exhort violent action against American military and citizenry until the stated grievances are reversed, noting "ulema have throughout Islamic history unanimously agreed that the jihad is an individual duty if the enemy destroys the Muslim countries."

Planning of the attacks
The idea for the September 11 plot came from Khalid Sheikh Mohammed, who first presented the idea to Osama bin Laden in 1996. At that point, Bin Laden and al-Qaeda were in a period of transition, having just relocated back to Afghanistan from Sudan. The 1998 African Embassy bombings and Bin Laden's 1998 fatwā marked a turning point, with bin Laden intent on attacking the United States.

In late 1998 or early 1999, bin Laden gave approval for Mohammed to go forward with organizing the plot. A series of meetings occurred in spring of 1999, involving Khalid Sheikh Mohammed, Osama bin Laden, and his deputy Mohammed Atef. Mohammed provided operational support for the plot, including target selections and helping arrange travel for the hijackers. Bin Laden overruled Mohammed, rejecting some potential targets such as the U.S. Bank Tower in Los Angeles because "there was not enough time to prepare for such an operation".

Bin Laden provided leadership for the plot, along with financial support, and was involved in selecting participants for the plot. Bin Laden initially selected Nawaf al-Hazmi and Khalid al-Mihdhar, both experienced jihadists who fought in Bosnia. Hazmi and Mihdhar arrived in the United States in mid-January 2000, after traveling to Malaysia to attend the Kuala Lumpur al-Qaeda Summit. In spring 2000, Hazmi and Mihdhar took flying lessons in San Diego, California, but both spoke little English, did not do well with flying lessons, and eventually served as "muscle" hijackers.

In late 1999, a group of men from Hamburg, Germany arrived in Afghanistan, including Mohamed Atta, Marwan al-Shehhi, Ziad Jarrah, and Ramzi Binalshibh. Bin Laden selected these men for the plot, as they were educated, could speak English, and had experience living in the west. New recruits were routinely screened for special skills, which allowed Al Qaeda leaders to also identify Hani Hanjour, who already had a commercial pilot's license, for the plot.

Hanjour arrived in San Diego on December 8, 2000, joining Hazmi. They soon left for Arizona, where Hanjour took refresher training. Marwan al-Shehhi arrived at the end of May 2000, while Atta arrived on June 3, 2000, and Jarrah arrived on June 27, 2000. Binalshibh applied several times for a visa to the United States, but as a Yemeni, he was rejected out of concerns he would overstay his visa and remain as an illegal immigrant. Binalshibh remained in Hamburg, providing coordination between Atta and Khalid Sheikh Mohammed. The three Hamburg cell members all took pilot training in south Florida.

In spring 2001, the muscle hijackers began arriving in the United States. In July 2001, Atta met with Binalshibh in Spain, where they coordinated details of the plot, including final target selection. Binalshibh also passed along Bin Laden's wish for the attacks to be carried out as soon as possible.

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

Bin Laden initially denied, but later admitted, involvement in the incidents. On September 16, 2001, bin Laden denied any involvement with the attacks by reading a statement which was broadcast by Qatar's Al Jazeera satellite channel: "I stress that I have not carried out this act, which appears to have been carried out by individuals with their own motivation." This denial was broadcast on U.S. news networks and worldwide.

In November 2001, U.S. forces recovered a videotape from a destroyed house in Jalalabad, Afghanistan, in which Osama bin Laden is talking to Khaled al-Harbi. In the tape, bin Laden admits foreknowledge of the attacks. The tape was broadcast on various news networks from December 13, 2001. His distorted appearance on the tape has been attributed to tape transfer artifact.

On December 27, 2001, a second bin Laden video was released. In the video, he states, "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", but he stopped short of admitting responsibility for the attacks.

Shortly before the U.S. presidential election in 2004, in a taped statement, bin Laden publicly acknowledged al-Qaeda's involvement in the attacks on the U.S. and admitted his direct link to the attacks. He said that the attacks were carried out because "we are free...and want to regain freedom for our nation. As you undermine our security we undermine yours." Osama bin Laden says he had personally directed the 19 hijackers. In the video, he says, "We had agreed with the Commander-General Muhammad Atta, Allah have mercy on him, that all the operations should be carried out within 20 minutes, before Bush and his administration notice." Another video obtained by Al Jazeera in September 2006 shows Osama bin Laden with Ramzi Binalshibh, as well as two hijackers, Hamza al-Ghamdi and Wail al-Shehri, as they make preparations for the attacks.

Khalid Sheikh Mohammed
The journalist Yosri Fouda of the Arabic television channel Al Jazeera reported that in April 2002, Khalid Sheikh Mohammed admitted his involvement, along with Ramzi Binalshibh, in the "Holy Tuesday operation". The 9/11 Commission Report determined that the animosity towards the United States felt by Khalid Sheikh Mohammed, the "principal architect" of the 9/11 attacks, stemmed "not from his experiences there as a student, but rather from his violent disagreement with U.S. foreign policy favoring Israel".

Mohamed Atta shared this motivation. Ralph Bodenstein, a former classmate of Atta described him as "most imbued actually about... U.S. protection of these Israeli politics in the region". Abdulaziz al-Omari, a hijacker aboard Flight 11 with Mohamed Atta, said in his video will, "My work is a message those who heard me and to all those who saw me at the same time it is a message to the infidels that you should leave the Arabian peninsula defeated and stop giving a hand of help to the coward Jews in Palestine."

Khalid Sheikh Mohammed was also an adviser and financier of a 1993 bombing, also on the World Trade Center. He is also the uncle of Ramzi Yousef, the lead bomber in that attack.

Khalid Sheikh Mohammed was arrested on March 1, 2003 in Rawalpindi, Pakistan by Pakistani security officials working with the CIA, and is currently being held at Guantanamo Bay. During US hearings in March 2007, which have been "widely criticized by lawyers and human rights groups as sham tribunals", Sheikh Mohammed again confessed his responsibility for the attacks, saying "I was responsible for the 9/11 operation, from A to Z." Mohammed made the confession after being subject to waterboarding.

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 Osama bin Laden, Khalid Sheikh Mohammed, Ramzi Binalshibh, Abu Turab al-Urduni and Mohammed Atef. To date, only peripheral figures have been tried or convicted for the attacks. Bin Laden has not yet been formally indicted for the attacks.

On September 26, 2005, the Spanish high court directed by judge Baltasar Garzón sentenced Abu Dahdah to 27 years of imprisonment 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.

Motive
The fatwas written or signed by Osama Bin Laden in 1996 and 1998 both demand the end of the presence of U.S. troops in Saudi Arabia. In the fatwa issued in 1998, bin Laden and others wrote: "For more than 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" (see February 22, 1998). [Nation, 2/15/1999] The attacks were consistent with the overall mission statement of al-Qaeda, as set out in the 1998 fatwā issued by Osama bin Laden, Ayman al-Zawahiri, Ahmed Refai Taha, Mir Hamzah, and Fazlur Rahman.

This statement begins by quoting the Koran as saying, "slay the pagans wherever ye find them" and extrapolates this to conclude that it is the "duty of every Muslim" to "kill Americans anywhere". Bin Laden elaborated on this theme in his "Letter to America" of October 2002: "You are the worst civilization witnessed by the history of mankind: You are the nation who, rather than ruling by the Shariah of Allah in its Constitution and Laws, choose to invent your own laws as you will and desire. You separate religion from your policies, contradicting the pure nature which affirms Absolute Authority to the Lord and your Creator."

Many of the eventual findings of the 9/11 Commission regarding motives have been supported by other experts. Counter-terrorism expert Richard A. Clarke explains in his 2004 book, Against All Enemies, that U.S. foreign policy decisions including "confronting Moscow in Afghanistan, inserting the U.S. military in the Persian Gulf", and "strengthening Israel as a base for a southern flank against the Soviets" contributed to al-Qaeda's motives. Others, such as Jason Burke, foreign correspondent for The Observer, focus on a more political aspect to the motive, stating that "bin Laden is an activist with a very clear sense of what he wants and how he hopes to achieve it. Those means may be far outside the norms of political activity [...] but his agenda is a basically political one."

A variety of scholarship has also focused on bin Laden's overall strategy as a motive for the attacks. For instance, correspondent Peter Bergen argues that the attacks were part of a plan to cause the United States to increase its military and cultural presence in the Middle East, thereby forcing Muslims to confront the "evils" of a non-Muslim government and establish conservative Islamic governments in the region. Michael Scott Doran, correspondent for Foreign Affairs, further emphasizes the "mythic" use of the term "spectacular" in bin Laden's response to the attacks, explaining that he was attempting to provoke a visceral reaction in the Middle East and ensure that Muslim citizens would react as violently as possible to an increase in U.S. involvement in their region.

Immediate response
The 9/11 attacks had immediate and overwhelming effects upon the American people. Many police officers and rescue workers elsewhere in the country took leaves of absence to travel to New York City to assist in the process of recovering bodies from the twisted remnants of the Twin Towers. Blood donations across the U.S. also saw a surge in the weeks after 9/11.

For the first time in history, SCATANA was invoked forcing all non-emergency civilian aircraft in the United States and several other countries including Canada to be immediately grounded, stranding tens of thousands of passengers across the world. Any international flights were closed to American airspace by the Federal Aviation Administration, causing about five hundred flights to be turned back or redirected to other countries. Canada received 226 of the diverted flights and launched Operation Yellow Ribbon to deal with the large numbers of grounded planes and stranded passengers.

Military operations following the attacks
At 2:40 p.m. in the afternoon of September 11, Secretary of Defense Donald Rumsfeld was issuing rapid orders to his aides to look for evidence of Iraqi involvement, according to notes taken by senior policy official Stephen Cambone. "Best info fast. Judge whether good enough hit S.H." — meaning Saddam Hussein — "at same time. Not only UBL" (Osama bin Laden), Cambone's notes quoted Rumsfeld as saying. "Need to move swiftly — Near term target needs — go massive — sweep it all up. Things related and not."

The NATO council declared that the attacks on the United States were considered an attack on all NATO nations and, as such, satisfied Article 5 of the NATO charter. Upon returning to Australia having been on an official visit to the US at the time of the attacks, Australian Prime Minister John Howard invoked Article IV of the ANZUS treaty. In the immediate aftermath of the attacks, the Bush administration announced a war on terrorism, with the stated goals of bringing Osama bin Laden and al-Qaeda to justice and preventing the emergence of other terrorist networks. These goals would be accomplished by means including economic and military sanctions against states perceived as harboring terrorists and increasing global surveillance and intelligence sharing.

The second-biggest operation of the U.S. Global War on Terrorism outside of the United States, and the largest directly connected to terrorism, was the overthrow of the Taliban rule of Afghanistan by a U.S.-led coalition. The United States was not the only nation to increase its military readiness, with other notable examples being the Philippines and Indonesia, countries that have their own internal conflicts with Islamic terrorism.

Domestic response
Following the attacks, President Bush's job approval rating soared to 90%. On September 20, 2001, the U.S. president spoke before the nation and a joint session of the United States Congress, regarding the events of that day, the intervening nine days of rescue and recovery efforts, and his intent in response to those events. In addition, the highly visible role played by New York City mayor Rudy Giuliani won him high praise nationally and in New York.

Many relief funds were immediately set up to assist victims of the attacks, with the task of providing financial assistance to the survivors of the attacks and to the families of victims, such as the Coalition of 9/11 Families. By the deadline for victim's compensation, September 11, 2003, 2,833 applications had been received from the families of those who were killed.

Contingency plans for the continuity of government and the evacuation of leaders were also implemented almost immediately after the attacks. Congress, however, was not told that the United States was under a continuity of government status until February 2002.

Within the United States, Congress passed and President Bush signed the Homeland Security Act of 2002, creating the Department of Homeland Security, representing the largest restructuring of the U.S. government in contemporary history. Congress also passed the USA PATRIOT Act, stating that it would help detect and prosecute terrorism and other crimes.

Civil liberties groups have criticized the PATRIOT Act, saying that it allows law enforcement to invade the privacy of citizens and eliminates judicial oversight of law-enforcement and domestic intelligence gathering. The Bush Administration also invoked 9/11 as the reason to initiate a secret National Security Agency operation, "to eavesdrop on telephone and e-mail communications between the United States and people overseas without a warrant".

Hate crimes
Numerous incidents of harassment and hate crimes were reported against Middle Easterners and other "Middle Eastern-looking" people in the days following the 9/11 attacks. Sikhs were also targeted because Sikh males usually wear turbans, which are stereotypically associated with Muslims. There were reports of verbal abuse, attacks on mosques and other religious buildings (including the firebombing of a Hindu temple) and assaults on people, including one murder: Balbir Singh Sodhi was fatally shot on September 15, 2001. He, like others, was a Sikh who was mistaken for a Muslim.

According to a study by Ball State University, people perceived to be Middle Eastern were as likely to be victims of hate crimes as followers of Islam during this time. The study also found a similar increase in hate crimes against people who may have been perceived as members of Islam, Arabs and others thought to be of Middle Eastern origin.

Muslim American reaction
Top Muslim organizations in the United States were swift to condemn the attacks on 9/11 and called "upon Muslim Americans to come forward with their skills and resources to help alleviate the sufferings of the affected people and their families". Top organizations include: Islamic Society of North America, American Muslim Alliance, American Muslim Council, Council on American-Islamic Relations, Islamic Circle of North America, and the Shari'a Scholars Association of North America. Along with massive monetary donations, many Islamic organizations launched blood drives and provided medical assistance, food, and shelter for victims.

International response
The attacks were denounced by mass media and governments worldwide. Across the globe, nations offered pro-American support and solidarity. Leaders in most Middle Eastern countries, and Afghanistan, condemned the attacks. Iraq was a notable exception, with an immediate official statement that "the American cowboys are reaping the fruit of their crimes against humanity". Another publicized exception was the celebration of some Palestinians and Serbians.

Tens of thousands of people attempted to flee Afghanistan following the attacks, fearing a response by the United States. Pakistan, already home to many Afghan refugees from previous Afghan conflict, closed its border with Afghanistan on September 17. Approximately one month after the attacks, the United States led a broad coalition of international forces in the removal of the Taliban regime for harboring the al-Qaeda organization. The Pakistani authorities moved decisively to align themselves with the United States in a war against the Taliban and al-Qaeda. Pakistan provided the United States a number of military airports and bases for its attack on the Taliban regime and arrested over 600 supposed al-Qaeda members, whom it handed over to the United States.

Numerous countries, including Canada, China, the United Kingdom, France, Russia, Germany, India and Pakistan introduced anti-terrorism legislation and froze the bank accounts of businesses and individuals they suspected of having al-Qaeda ties. Law enforcement and intelligence agencies in a number of countries, including Italy, Malaysia, Indonesia, and the Philippines arrested people they labeled terrorist suspects for the stated purpose of breaking up militant cells around the world.

In the U.S., this aroused some controversy, as critics such as the Bill of Rights Defense Committee argued that traditional restrictions on federal surveillance (e.g. COINTELPRO's monitoring of public meetings) were "dismantled" by the USA PATRIOT Act. Organizations such as the American Civil Liberties Union and Liberty argued that certain civil rights protections were also being circumvented.

The United States set up a detention center at Guantánamo Bay, Cuba to hold whom they defined as "illegal enemy combatants". The legitimacy of these detentions has been questioned by, among others, the European Parliament, the Organization of American States, and Amnesty International.

The international events and reactions immediately after the attacks affected the impact of the World Conference against Racism 2001, which had ended in discord and international recriminations just three days before.

As in the United States, the aftermath of the attacks saw racial tensions increase in other countries between Muslims and non Muslims. The most notable example occurred in the United Kingdom, where on September 21, teenager Ross Parker was murdered by a gang of Muslims in a racist attack.

Conspiracy theories
Proponents of 9/11 conspiracy theories have suggested that individuals inside the United States possessed detailed information about the attacks and deliberately chose not to prevent them, or that individuals outside of al-Qaeda planned, carried out, or assisted in the attacks. Some conspiracy theorists claim the World Trade Center did not collapse because of the crashing planes but was demolished with explosives.

This controlled demolition hypothesis is rejected by the National Institute of Standards and Technology and by the American Society of Civil Engineers, who, after their research, both concluded that the impacts of jets at high speeds in combination with subsequent fires caused the collapse of both Towers.

US foreign policy and relations shifts
As a result of the 9/11 attack, US foreign policy shifted abruptly and dramatically. As noted above, the attacks resulted directly in the declaration of the US War in Afghanistan beginning in 2001, even though the Taliban offered to put bin Laden on trial in a third country.

During the first few years after the 9/11 attacks, international support for an aggressive response by the US ran high, however, as the years of the Bush administration seemed to run on without producing any of the promised results, i.e. the capture of Bin Laden, or the reduction of terrorism by Islamic extremists, international support for Bush administration policies seemed to wither and to even turn antagonistic.

Ultimately, Bush left office with an international approval rating of his foreign policies of less than 20%. After the American 2008 election results indicated that Americans had grown weary of pursuing aggressive militaristic policies as a response to the 9/11 attacks, and after a government had been elected that had pledged to reverse such policies, popular international support for America began to rebound.

Economic aftermath


The attacks had a significant economic impact on the United States and world markets. The New York Stock Exchange (NYSE), the American Stock Exchange (AMEX), and NASDAQ did not open on September 11 and remained closed until September 17. When the stock markets reopened, the Dow Jones Industrial Average (DJIA) stock market index fell 684 points, or 7.1%, to 8921, a record-setting one-day point decline.

By the end of the week, the DJIA had fallen 1,369.7 points (14.3%), its then-largest one-week point drop in history, though later surpassed in 2008 during the global financial crisis. U.S. stocks lost $1.4 trillion in value for the week. This is equivalent to $ in present day terms.

Economist and Crisis Consultant Randall Bell was retained by the city and state of New York to compute the economic damages to The World Trade Center site. He writes in his book, Strategy 360, "The World Trade Center damages, estimated by the New York City Mayor's Office, were staggering: Clean up and stabilization of the WTC site - $9.0 billion; Repairing and replacing damaged infrastructure - $9.0 billion; Rebuilding the World Trade Center as smaller buildings - $6.7 billion; Repairing and restoring other damaged buildings - $5.3 billion; Lost rent of the destroyed buildings - $1.75 billion."

In New York City, about 430,000 job-months and $2.8 billion in wages were lost in the three months following the 9/11 attacks. The economic effects were mainly focused on the city's export economy sectors. The city's GDP was estimated to have declined by $27.3 billion for the last three months of 2001 and all of 2002. The Federal government provided $11.2 billion in immediate assistance to the Government of New York City in September 2001, and $10.5 billion in early 2002 for economic development and infrastructure needs.

The 9/11 attacks also hurt small businesses in Lower Manhattan near the World Trade Center, destroying or displacing about 18,000 of them. Assistance was provided by Small Business Administration loans and federal government Community Development Block Grants and Economic Injury Disaster Loans. Some 31.9 million square feet of Lower Manhattan office space was damaged or destroyed.

Many wondered whether these jobs would return, and the damaged tax base recover. Studies of the economic effects of 9/11 show that the Manhattan office real-estate market and office employment were less affected than initially expected because of the financial services industry's need for face-to-face interaction.

North American air space was closed for several days after the attacks and air travel decreased upon its reopening, leading to nearly a 20% cutback in air travel capacity, and exacerbating financial problems in the struggling U.S. airline industry.

Health effects
The thousands of tons of toxic debris resulting from the collapse of the Twin Towers consisted of more than 2,500 contaminants, including known carcinogens. This has led to debilitating illnesses among rescue and recovery workers, which many claim to be directly linked to debris exposure. For example, NYPD Officer Frank Macri died of lung cancer that spread throughout his body on September 3, 2007; his family contends the cancer is the result of long hours on the site and they have filed for line-of-duty death benefits, which the city has yet to rule on.

Health effects have also extended to some residents, students, and office workers of Lower Manhattan and nearby Chinatown. Several deaths have been linked to the toxic dust caused by the World Trade Center's collapse and the victims' names will be included in the World Trade Center memorial. There is also scientific speculation that exposure to various toxic products in the air may have negative effects on fetal development. Due to this potential hazard, a notable children's environmental health center is currently analyzing the children whose mothers were pregnant during the WTC collapse, and were living or working near the World Trade Center towers.

Legal disputes over the attendant costs of illnesses related to the attacks are still in the court system. On October 17, 2006, federal judge Alvin Hellerstein rejected New York City's refusal to pay for health costs for rescue workers, allowing for the possibility of numerous suits against the city. Government officials have been faulted for urging the public to return to lower Manhattan in the weeks shortly following the attacks. Christine Todd Whitman, administrator of the EPA in the aftermath of the attacks, was heavily criticized for incorrectly saying that the area was environmentally safe. President Bush was criticized for interfering with EPA interpretations and pronouncements regarding air quality in the aftermath of the attacks. In addition, Mayor Giuliani was criticized for urging financial industry personnel to return quickly to the greater Wall Street area.

FBI investigation
Immediately after the attacks, the Federal Bureau of Investigations started PENTTBOM, the largest criminal inquiry in the history of the United States. The FBI told the U.S. Senate that there is "clear and irrefutable" evidence linking Al Qaida and Bin Laden to the attacks.

9/11 Commission
The National Commission on Terrorist Attacks Upon the United States (9/11 Commission), chaired by former New Jersey Governor Thomas Kean, was formed in late 2002 to prepare a thorough account of the circumstances surrounding the attacks, including preparedness for, and the immediate response to, the attacks. On July 22, 2004, the 9/11 Commission issued the 9/11 Commission Report. The commission and its report have been subject to criticism.

Collapse of the World Trade Center
A federal technical building and fire safety investigation of the collapses of the Twin Towers and 7 WTC has been conducted by the United States Department of Commerce's National Institute of Standards and Technology (NIST). The goals of this investigation were to determine why the buildings collapsed, the extent of injuries and fatalities, and the procedures involved in designing and managing the World Trade Center. The investigation into the collapse of 1 WTC and 2 WTC was concluded in October 2005, and the investigation into the collapse of 7 WTC concluded in August 2008.

The report concluded that the fireproofing on the Twin Towers' steel infrastructures was blown off by the initial impact of the planes and that, if this had not occurred, the towers would likely have remained standing. A study published by researchers of Purdue University confirmed that, if the thermal insulation on the core columns would have been scoured off and column temperatures were elevated to approximately 700 °C, the fire would be sufficient to initiate collapse.

W. Gene Corley, the director of the original investigation, commented that "the towers really did amazingly well. The terrorist aircraft didn’t bring the buildings down; it was the fire which followed. It was proven that you could take out two thirds of the columns in a tower and the building would still stand." The fires weakened the trusses supporting the floors, making the floors sag. The sagging floors pulled on the exterior steel columns to the point where exterior columns bowed inward. With the damage to the core columns, the buckling exterior columns could no longer support the buildings, causing them to collapse. In addition, the report asserts that the towers' stairwells were not adequately reinforced to provide emergency escape for people above the impact zones. NIST concluded that uncontrolled fires in 7 WTC caused floor beams and girders to heat and subsequently "caused a critical support column to fail, initiating a fire-induced progressive collapse that brought the building down".

Internal review of the CIA
The Inspector General of the CIA conducted an internal review of the CIA's pre-9/11 performance, and was harshly critical of senior CIA officials for not doing everything possible to confront terrorism, including failing to stop two of the 9/11 hijackers, Nawaf al-Hazmi and Khalid al-Mihdhar, as they entered the United States and failing to share information on the two men with the FBI.

In May 2007, senators from both the Democratic Party and the Republican Party drafted legislation that would openly present an internal CIA investigative report. One of the backers, Senator Ron Wyden stated "The American people have a right to know what the Central Intelligence Agency was doing in those critical months before 9/11.... I am going to bulldog this until the public gets it." The report investigates the responsibilities of individual CIA personnel before and after the 9/11 attacks. The report was completed in 2005, but its details have never been released to the public.

Rebuilding
On the day of the attacks, New York City mayor Rudy Giuliani proclaimed, "We will rebuild. We're going to come out of this stronger than before, politically stronger, economically stronger. The skyline will be made whole again." The Lower Manhattan Development Corporation, tasked with coordinating rebuilding efforts at the World Trade Center site, was criticized for doing little with the enormous funding directed to the rebuilding efforts.

On the sites of the destroyed buildings, one, 7 World Trade Center, has a new office tower which was completed in 2006. The 1 World Trade Center is currently under construction at the site and at 1,776 ft (541 m) upon completion in 2011, will become one of the tallest buildings in North America, behind only the CN Tower in Toronto.

Three more towers were expected to be built between 2007 and 2012 on the site, and will be located one block east of where the original towers stood. After the late-2000s recession, the site's owners said that construction of new towers could be delayed until 2036. The damaged section of the Pentagon was rebuilt and occupied within a year of the attacks.

Memorials
In the days immediately following the attacks, many memorials and vigils were held around the world. In addition, pictures were placed all over Ground Zero. A witness described being unable to "get away from faces of innocent victims who were killed. Their pictures are everywhere, on phone booths, street lights, walls of subway stations. Everything reminded me of a huge funeral, people quiet and sad, but also very nice. Before, New York gave me a cold feeling; now people were reaching out to help each other.”

One of the first memorials was the Tribute in Light, an installation of 88 searchlights at the footprints of the World Trade Center towers which projected two vertical columns of light into the sky. In New York, the World Trade Center Site Memorial Competition was held to design an appropriate memorial on the site. The winning design, Reflecting Absence, was selected in August 2006, and consists of a pair of reflecting pools in the footprints of the towers, surrounded by a list of the victims' names in an underground memorial space. Plans for a museum on the site have been put on hold, following the abandonment of the International Freedom Center in reaction to complaints from the families of many victims.

The Pentagon Memorial was completed and opened to the public on the seventh anniversary of the attacks, September 11, 2008. It consists of a landscaped park with 184 benches facing the Pentagon. When the Pentagon was repaired in 2001–2002, a private chapel and indoor memorial were included, located at the spot where Flight 77 crashed into the building.

At Shanksville, a permanent Flight 93 National Memorial is planned to include a sculpted grove of trees forming a circle around the crash site, bisected by the plane's path, while wind chimes will bear the names of the victims. A temporary memorial is located 500 yd from the crash site. New York City firefighters donated a memorial to the Shanksville Volunteer Fire Department. It is a cross made of steel from the World Trade Center and mounted on top of a platform shaped like the Pentagon. It was installed outside the firehouse on August 25, 2008.

Many other permanent memorials are being constructed elsewhere, and scholarships and charities have been established by the victims' families, along with many other organizations and private figures.

If American society at large payed their tributes by erecting memorials that showed their sympathy with the victims, the community of creative artists showed differing sensibilities. Although in recent decades art has been politicized, with sociopolitical problems inspiring much artistic activity, the art community was distinctly chary in responding to the September 11 terrorist attacks. According to Commentary, only one significant monumental artistic response to 9/11 was made: Eric Fischl's bronze sculpture Tumbling Woman, which was installed in Rockefeller Center one year later. The figure, however, was stripped of any sense of poignancy or dignity, "showing her landing ridiculously on her head, with all the bathos of an unsightly spill in the tub." The statue gave offense, and it was removed promptly. Most other art that followed 9/11 "suffered from the same moral incoherence". Commentary identifies the reigning political bias among artists as the explanation. It suspects that the lack of noteworthy attempts to humanize the victims may be due to "fear that it might dehumanize their killers".

Multimedia

 * CNN.com - Video archive, including the first and second planes.
 * Inside 9/11 - National Geographic Society
 * Time.com - 'Shattered: a remarkable collection of photographs', James Nachtwey
 * September 11, 2001 Screenshot Archive - Database of 230 screenshots from news sites around the world.

Memorials

 * CNN September 11 Memorial - List of victims, and photos.

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