Marwan al-Shehhi in the context of "9/11 attacks"

Terrorism, in its broadest sense, is the use of violence against non-combatants to achieve political or ideological aims. The term is used in this regard primarily to refer to intentional violence during peacetime or in the context of war against non-combatants. There are various different definitions of terrorism, with no universal agreement about it. Different definitions of terrorism emphasize its randomness, its aim to instill fear, and its broader impact beyond its immediate victims.

Modern terrorism, evolving from earlier iterations, employs various tactics to pursue political goals, often leveraging fear as a strategic tool to influence decision makers. By targeting densely populated public areas such as transportation hubs, airports, shopping centers, tourist attractions, and nightlife venues, terrorists aim to instill widespread insecurity, prompting policy changes through psychological manipulation and undermining confidence in security measures.

The September 11 attacks, colloquially and perhaps more commonly known as 9/11, were four coordinated Islamist terrorist suicide attacks by al-Qaeda against the United States in 2001. Nineteen terrorists hijacked four commercial airliners, then flew one into each of the Twin Towers at the World Trade Center in New York City, and another into the Pentagon, the headquarters of the U.S. Department of Defense, in Arlington County, Virginia. The fourth plane crashed in a rural Pennsylvania field during a passenger revolt. In response to the attacks, the United States launched and waged the global war on terror over two decades, with the mission to eliminate hostile groups deemed terrorist organizations, and the governments purported to support them.

Ringleader and hijacker Mohamed Atta flew American Airlines Flight 11 into the North Tower of the World Trade Center complex at 8:46 a.m. Seventeen minutes later at 9:03 a.m., hijacker Marwan al-Shehhi flew United Airlines Flight 175 into the South Tower. Both collapsed within an hour and forty-two minutes, destroying the remaining five structures in the complex. Hijacker Hani Hanjour flew American Airlines Flight 77 into the Pentagon at 9:37 a.m., causing a partial collapse. The fourth and final flight, United Airlines Flight 93, flown by hijacker Ziad Jarrah, was believed by investigators to target either the United States Capitol or the White House. Alerted to the previous attacks, the passengers revolted against the hijackers who crashed the aircraft into a field near Shanksville, Pennsylvania, at 10:03 a.m. The Federal Aviation Administration ordered an indefinite ground stop for all air traffic in U.S. airspace, preventing any further aircraft departures until September 13 and requiring all airborne aircraft to return to their point of origin or divert to Canada. The actions undertaken in Canada to support incoming aircraft and their occupants were collectively titled Operation Yellow Ribbon.

The aircraft hijackers in the September 11 attacks were 19 men affiliated with al-Qaeda, a jihadist organization based in Afghanistan. They hailed from four countries; 15 of them were citizens of Saudi Arabia, two were from the United Arab Emirates, one was from Egypt, and one from Lebanon. To carry out the attacks, the hijackers were organized into four teams each led by a pilot-trained hijacker who would commandeer the flight with three or four "muscle hijackers" who were trained to help subdue the pilots, passengers, and crew. Each team was assigned to a different flight and given a unique target to crash their respective planes into. Mohamed Atta was the assigned ringleader over all four groups.

The first hijackers to arrive in the United States were Khalid al-Mihdhar and Nawaf al-Hazmi, who settled in San Diego County, California, in January 2000. They were followed by three hijacker-pilots, Hamburg cell members Mohamed Atta, Marwan al-Shehhi, and Ziad Jarrah in mid-2000 to undertake flight training at Huffman Aviation flight-training school in Venice, Florida. The fourth hijacker-pilot, Hani Hanjour, who was not a member of the Hamburg cell, arrived in San Diego in December 2000. The rest of the "muscle hijackers" arrived in early- and mid-2001.

United Airlines Flight 175 was an American domestic passenger flight from Logan International Airport in Boston to Los Angeles International Airport in California that was hijacked by five al-Qaeda terrorists on the morning of September 11, 2001, as part of the September 11 attacks. The aircraft involved, a Boeing 767-200 carrying 51 passengers and 9 crew members (excluding the 5 hijackers), was deliberately crashed into the South Tower of the World Trade Center in New York City, killing everyone aboard and causing the deaths of more than 600 people in the South Tower's upper levels in addition to an unknown number of civilians and emergency personnel on floors beneath the impact zone. Flight 175 is the second-deadliest plane crash in aviation history, surpassed only by American Airlines Flight 11.

Flight 175 departed from Logan Airport at 08:14. Twenty-eight minutes into the flight, the hijackers injured several crew members, forced their way into the cockpit, and murdered both pilots while moving anyone who remained to the rear of the aircraft. Lead hijacker Marwan al-Shehhi, who had trained as a pilot for the purposes of the attacks, was able to usurp the flight controls once the hijackers killed the captain and first officer. Unlike the team on American Airlines Flight 11, the terrorists aboard Flight 175 did not switch off the plane's transponder when they took over the cockpit. Thus, the aircraft was visible on New York Center's radar, which depicted the deviation from its assigned flight path before controllers took notice four minutes later at 08:51 EDT. Upon realizing, the ATC workers immediately made several unsuccessful attempts to contact the cockpit of the hijacked airliner, which twice nearly collided with other planes as it recklessly flew toward New York City. In the interim, three people were able to get through to their family members and colleagues on the ground, passing on information to do with the hijackers as well as casualties suffered by the flight crew.

Mohamed Atta (1 September 1968 – 11 September 2001) was an Egyptian engineer and terrorist hijacker for al-Qaeda. Ideologically a pan-Islamist, he was the ringleader of the September 11 attacks and served as the hijacker-pilot of American Airlines Flight 11, which he flew into the North Tower of the original World Trade Center as part of coordinated suicide attacks. Aged 33, he was the oldest of the 19 hijackers who took part in the mission. Before the attacks, he worked as a civil engineer.

Born and raised in Egypt, Atta studied architecture at Cairo University, graduating in 1990, and pursued postgraduate studies in Germany at the Hamburg University of Technology. In Hamburg, Atta became involved with the al-Quds Mosque where he met Marwan al-Shehhi, Ramzi bin al-Shibh, and Ziad Jarrah, together forming the Hamburg cell. Atta disappeared from Germany for periods of time, embarking on the hajj in 1995 but also meeting Osama bin Laden and other top al-Qaeda leaders in Afghanistan from late 1999 to early 2000. Atta and the other Hamburg cell members were recruited by bin Laden and Khalid Sheikh Mohammed for a "planes operation" in the United States.

Ziad Samir Jarrah (Arabic: زياد سمير جراح; 11 May 1975 – 11 September 2001), also known as Ziad al-Jarrah, was a Lebanese terrorist who was a member of al-Qaeda, a pan-Islamist militant organization. During the 11 September attacks in 2001, he was one of 19 al-Qaeda members who hijacked four American commercial flights in an attempt to crash them into national landmarks in the country. Jarrah's group hijacked United Airlines Flight 93, departing Newark, New Jersey, for San Francisco, but they failed to reach their target when the plane crashed.

Jarrah grew up in a secular and wealthy family living in Beirut during the Lebanese Civil War (1975-1990). In 1996, he moved to Germany to study aerospace engineering at the Hamburg University of Applied Sciences. In Hamburg, he became part of a clandestine cell system known as the Hamburg cell with fellow hijackers Mohamed Atta and Marwan al-Shehhi, among many others. In 1999, member Ramzi bin al-Shibh took the cell to Afghanistan to meet al-Qaeda's leader, Osama bin Laden, where they were instructed to receive flight training. In 2000, Jarrah enrolled in a flight school in Florida.

The Hamburg cell (German: Hamburger Zelle; Arabic: خلية هامبورغ, Khalia Hamburh) were a clandestine cell system of eleven Islamist terrorists living in Hamburg, Germany, in the late 1990s. In 1999, they traveled to Afghanistan to meet with leaders of the militant organization al-Qaeda, and then returned to Hamburg to work on al-Qaeda's plan for terrorist attacks against the United States. This led to the September 11 attacks in 2001, in which four American airliners were hijacked in an attempt to crash them into important landmarks in the country.

Germany, the U.S., and the United Nations collectively consider eleven people to have been members. Three of them—Mohamed Atta, Marwan al-Shehhi, and Ziad Jarrah—were hijackers of American Airlines Flight 11, United Airlines Flight 175, and United Airlines Flight 93, respectively. In 2002, Ramzi bin al-Shibh stated that only he and those three men were members. However, authorities also list: Abdelghani Mzoudi, Mamoun Darkazanli, Mohammed Haydar Zammar, Mounir el-Motassadeq, Naamen Meziche, Said Bahaji, and Zakariya Essabar.