September 11 attacks

The September 11 attacks, or 9/11, were a series of coordinated attacks by the Islamic terrorist group al-Qaeda on the United States in 2001. Nineteen terrorists hijacked four airplanes and used them as weapons. Two planes crashed into the Twin Towers of the World Trade Center in New York City, causing both towers to collapse. Another plane hit the Pentagon in Virginia, which is the headquarters of the United States Department of Defense. The fourth plane was headed toward a government building but was brought down by the passengers who fought back; it crashed in a field in Pennsylvania.

These attacks led the United States to start what is called the war on terror, a long effort to fight against groups considered terrorists. Many countries changed their laws and increased security to prevent future attacks. The events of 9/11 had a major effect on the world, changing how countries think about safety and security.

In memory of those who were lost, several memorials were built, including the National September 11 Memorial & Museum in New York City. The attacks remain one of the most serious terrorist acts in history, and they continue to influence policies and discussions about safety and international relations around the world.

Background

Osama bin Laden

Main article: Osama bin Laden

Osama bin Laden was the leader of the group al-Qaeda, which carried out the September 11 attacks in 2001. In 1996, he declared a struggle against the United States, objecting to American troops being stationed in Arabia. He later moved to Afghanistan, where he planned the attacks on the World Trade Center in New York City and the Pentagon in Arlington, Virginia, using hijacked planes. Though he initially denied involvement, he later admitted to organizing the attacks.

Motives

Main article: Motives for the September 11 attacks

Further information: Fatwas of Osama bin Laden and Political views of Osama bin Laden

Bin Laden’s motives included opposition to American support of Israel, sanctions against Iraq, and the presence of U.S. forces in Saudi Arabia. He believed these actions harmed Muslims and aimed to force the U.S. to change its policies. He also wanted to strike symbols of America’s power to weaken its economy and military influence.

Khalid Sheikh Mohammed and other al-Qaeda members

Main article: Khalid Sheikh Mohammed

Khalid Sheikh Mohammed was the main planner of the September 11 attacks. He had previously helped organize a bombing of the World Trade Center in 1993. He worked with other al-Qaeda members to develop the plan, choosing targets and helping to coordinate the hijackers. His anger toward U.S. policies, especially support for Israel, influenced his actions.

Planning

Main article: Planning of the September 11 attacks

The attacks were carefully planned over several years. Bin Laden provided leadership and support, while other al-Qaeda members helped with details such as selecting targets and arranging travel for the hijackers. Some of the future hijackers began training at flight schools in the United States as early as 2000. The group coordinated their efforts to ensure the attacks would be carried out successfully.

Prior intelligence

Main article: September 11 intelligence before the attacks

Before the attacks, there were several warnings and pieces of information that suggested something major might happen. Intelligence agencies knew that some al-Qaeda members were in the United States, and there were concerns about activities at flight schools. However, this information was not always shared properly among different agencies, which delayed efforts to prevent the attacks.

Attacks

Early on the morning of Tuesday, September 11, 2001, nineteen hijackers took control of four commercial airliners. They used these planes to attack important buildings in the United States.

The hijackers flew two planes into the Twin Towers at the World Trade Center in New York City. A third plane hit the Pentagon, which is the headquarters of the United States Department of Defense, in Virginia. The fourth plane was headed toward Washington D.C., but the passengers fought back, and the plane crashed in a field instead.

The attacks caused the collapse of the Twin Towers and parts of the Pentagon. Many people sadly lost their lives, and the events had a big impact on the United States and the world.

Main article: Rescue and recovery effort after the September 11 attacks on the World Trade Center

Reactions

The September 11 attacks led to many immediate and lasting responses around the world. In the United States, President George W. Bush addressed the nation and Congress, promising to defend freedom against terrorism. Many relief funds were created to help survivors and families of victims. The U.S. government also passed important new laws, such as the USA PATRIOT Act, to help prevent future terrorist attacks.

Internationally, most countries condemned the attacks and offered support to the United States. Leaders in many Middle Eastern nations also spoke out against the attacks. However, some reactions were mixed, with reports of celebrations in parts of the Palestinian territories. Overall, the attacks led to increased tensions between Muslim and non-Muslim communities in many countries.

Aftermath

Main article: Aftermath of the September 11 attacks

Hundreds of thousands of tons of toxic dust were spread across Lower Manhattan when buildings collapsed. This dust caused many health problems for people nearby. The government worked to help those affected and created programs to support people with long-term health issues.

The attacks also had big effects on the economy. Stock markets dropped, and many jobs were lost in New York City. The government provided aid to help businesses and workers. Air travel also changed, with new safety measures put in place to keep everyone safe.

Investigations

FBI

Further information: Hijackers in the September 11 attacks

Right after the September 11 attacks, the Federal Bureau of Investigation (FBI) began one of the biggest criminal investigations in U.S. history. Many FBI agents worked on the case and followed hundreds of thousands of clues. The FBI found clear evidence linking the group al-Qaeda and a man named bin Laden to the attacks.

The FBI quickly learned the names of the hijackers when bags carried by one of them, Mohamed Atta, were found at an airport. These bags had important papers that helped the FBI learn more about the attackers.

CIA

Further information: September 11 intelligence before the attacks

In 2004, an official from the Central Intelligence Agency (CIA) reviewed how the agency worked before the September 11 attacks. He said that some senior CIA officers had not done all they could to stop two of the attackers when they entered the United States.

Congressional inquiry

Main article: Joint Inquiry into Intelligence Community Activities before and after the Terrorist Attacks of September 11, 2001

In 2002, two groups of U.S. lawmakers worked together to study how U.S. intelligence agencies handled information before the attacks. Their report showed that the FBI and CIA did not use information they had to stop the attacks. Some pages of the report were kept secret for many years.

9/11 Commission

Main articles: 9/11 Commission and 9/11 Commission Report

See also: Criticism of the 9/11 Commission

In 2002, a special commission was created to look closely at the September 11 attacks. The commission made a big report in 2004. The report said the attacks were carried out by al-Qaeda and pointed out problems in how U.S. security and intelligence agencies worked together.

National Institute of Standards and Technology

Main article: NIST World Trade Center Disaster Investigation

See also: 7 World Trade Center (1987–2001) § 9/11 and collapse

Scientists studied why the buildings fell down after the attacks. They found that fires played a big role in making the buildings collapse. The fires made parts of the buildings weak, which caused them to fall. They also looked at how to make buildings safer in the future.

Rebuilding and memorials

Reconstruction

Main articles: Rescue and recovery effort after the September 11 attacks on the World Trade Center and Construction of One World Trade Center

Further information: World Trade Center (2001–present) and World Trade Center site

After the attacks in 2001, efforts began quickly to clean up the site and rebuild. By the end of May 2002, the World Trade Center site was cleared. The damaged part of the Pentagon was repaired and ready for use within a year. New buildings were constructed over many years. The tallest of these, One World Trade Center, reached its full height in 2013 and opened to the public in 2014. Today, several other office towers are also part of the rebuilt World Trade Center area.

Memorials

Main article: Memorials and services for the September 11 attacks

In the days after the attacks, people around the world held special events to honor those who were lost. One famous memorial is called the Tribute in Light, which uses bright searchlights to mark where the old towers stood. At the World Trade Center site, a quiet space with reflecting pools and the names of victims reminds us of the people who were lost. A museum there opened in 2014 to help people learn about that day.

Other memorials exist too, like one at the Pentagon and another near where a plane crashed in Pennsylvania. Every year on the anniversary of the attacks, people gather to remember those who were lost and to show respect for their lives.