Planning of the September 11 attacks

In the United States on September 11, 2001 (9/11), 19 terrorists from al-Qaeda hijacked four airplanes in an attempt to crash them into American landmarks. American Airlines Flight 11 and United Airlines Flight 175 crashed into the World Trade Center, and American Airlines Flight 77 was crashed into the Pentagon. United Airlines Flight 93 was intended to be crashed into the U.S. Capitol or White House, but the hijackers intentionally crashed it into a field in Pennsylvania instead due to a passenger revolt.

Initially, al-Qaeda official Khalid Sheikh Mohammed planned to bomb multiple airliners departing Asia for the U.S. in 1995; the plot was foiled by Manila police before it was enacted. In 1996, he redesigned the plan, wanting nine U.S. airliners to be crashed into U.S. landmarks; al-Qaeda's leader, Osama bin Laden, rejected the plan over its complexity. In 1999, the pair and Mohammed Atef reworked it into what was ultimately carried out on 9/11.

Al-Qaeda then came into contact with the Hamburg cell, a terrorist cell in Germany led by Mohamed Atta. Some of the cell's members then visited camps in Afghanistan where al-Qaeda told them the plan, before the cell regrouped in Germany to work on it. Three of the members eventually piloted the hijacked planes on 9/11: Atta (Flight 11), Marwan al-Shehhi (175), and Ziad Jarrah (93). Flight 77's hijacker-pilot Hani Hanjour was not involved.

At least 19 men chosen by al-Qaeda entered the U.S. in 2000 and 2001. In addition, a potential 20th hijacker named Zacarias Moussaoui was arrested in Minnesota in August 2001. The 19 others split into four groups, and got tickets for four commercial flights on 9/11. During the hijackings, certain members of the groups attacked their respective flights' aircrews, likely using box cutters and mace, which let the others enter the planes' cockpits.

2,977 victims, plus all of the hijackers, died in the attacks. Many of the remaining conspirators in al-Qaeda were captured, then tortured during U.S. interrogations at CIA black sites or the Guantanamo Bay detention camp. Multiple federal investigations were made into 9/11, such as PENTTBOM and the 9/11 Commission. Investigators are split on if Saudi Arabia financed the attacks.

Background

thumb|266x266px|[[Osama bin Laden]]In the Soviet–Afghan War (1979–1989), Muslim-majority Afghanistan was invaded by the mostly non-Muslim Soviet Union. Osama bin Laden, a Saudi Islamist connected to the royal House of Saud, left his country to organize the Afghan mujahideen, Muslims who fought the Soviets as jihadists; those who engage in jihad, Islamic religious struggle, are called mujahideen. For that purpose, bin Laden and Abdullah Yusuf Azzam founded Maktab al-Khidamat (MaK). After the Soviets withdrew from Afghanistan in 1989, Azzam was assassinated in Pakistan. Bin Laden then took full control of MaK, which was absorbed into his organization al-Qaeda.

Due to bin Laden's beliefs, in 1991, the royals exiled him from Saudi Arabia. He moved to Sudan, where he may have had al-Qaeda get involved in the 1993 assault on U.S. troops in Somalia. In 1996, under Saudi and American pressure, Sudan exiled him from their country. Bin Laden returned to Afghanistan, which, by then, was run by the Taliban. They allowed al-Qaeda to use the country as its base of operations.

In 1996, bin Laden issued a fatwa calling for the American troops stationed in Saudi Arabia to leave.

In August 1998, al-Qaeda bombed two U.S. embassies in Kenya and Tanzania. In 1999, the organization failed in an attempt to bomb Los Angeles International Airport (LAX) on New Year's Eve—one of many attacks they had planned to around the start of the new millennium. Shortly before New Year's, the planned perpetrator, Ahmed Ressam, tried to drive into the U.S. at the Canadian border, but border guards caught him with bomb-making material in his car. al-Qaeda also failed in an attempt to bomb USS The Sullivans, a U.S. Navy ship, on January 3, 2000. In October, they successfully bombed USS Cole while she docked in Yemen, by sailing a small radio-controlled boat up to her, then detonating a remote-controlled bomb that was on the boat.

1990s–1996: Origins of the hijacking plan

thumb|266x266px|[[Khalid Sheikh Mohammed upon his capture in 2003|left]]In the early 1990s, a Pakistani veteran of the Afghan mujahideen, Khalid Sheikh Mohammed, rose through the ranks of al-Qaeda to became a top lieutenant of bin Laden. During that time, he devised a plan for a series of terrorist attacks by al-Qaeda targeting airliners, which he codenamed "Bojinka"—allegedly a "nonsense word" he once heard in Afghanistan. In the "Bojinka plot", al-Qaeda and another group, Jemaah Islamiyah, planned for eleven planes departing Southeast Asia towards the United States to simultaneously be destroyed over the Pacific, via liquid bombs made by mixing chemicals. Pope John Paul II would be assassinated in the process.

In 1993, a group of al-Qaeda members that included Mohammed's nephew, Ramzi Yousef, bombed the underground portion of the World Trade Center (WTC) business complex in New York City, killing six people and injuring more than a thousand. Afterwards, in his apartment in Manila, Yousef and other conspirators started mixing chemicals to make the bombs for the Bojinka attacks. In 1994, Yousef rehearsed the bombings twice. One was set off at a Manila theater, the other inside Philippines Airlines Flight 434 mid-flight, killing one passenger. Yousef was captured by Pakistan in February 1995, and turned to over to the U.S., where he was sentenced to life in prison. Investigators publicized the plan for the Bojinka plot. The Los Angeles Times reported in May that Western and Philippine officials were concerned about former Afghan mujahideen fighters who planned to commit terrorist acts in the name of Islam. Mohammed continued working on his idea regarding hijacked airliners. Al-Qaeda members would hijack ten airplanes departing from across the U.S., and nine would be crashed into: the World Trade Center; the U.S. Capitol and the FBI's headquarters, in Washington, D.C.; the Pentagon in Arlington County, Virginia; the CIA's headquarters in Langley, Virginia; the Columbia Center in Seattle; the Library Tower (now the U.S. Bank Tower) in Los Angeles; and an undetermined nuclear power plant. At the time, the Columbia Center and the Library Tower were the tallest skyscrapers in Washington state and California, respectively. Nothing came of the plan at the time, as bin Laden rejected it for being too elaborate. Mohammed later recalled that, "as we studied various targets, nuclear facilities arose as a key option", but they were discarded after concerns that the plan would "get out of hand".

thumb|[[Mohammed Atef]]

In late 1998 or early 1999, bin Laden summoned Mohammed to Kandahar, Afghanistan, and approved for him to proceed with a scaled back version of the plan. In the spring of 1999, bin Laden, Mohammed, and bin Laden's deputy, Mohammed Atef, held a series of meetings where they designed the final version of the general plan, which was ultimately carried out on 9/11. They listed potential targets that each symbolized to them the U.S.' global power, including: the World Trade Center, representing America's economy; the Pentagon, its military; the U.S. Capitol, its support of Israel; and the White House in D.C., its politics.

1990s–2000: Hamburg cell

thumb|250x250px|[[Mohamed Atta (left) talking to fellow students in Germany in 1993]]

In 1992, an Egyptian architect named Mohamed Atta moved to Germany to study urban planning at university in Hamburg. Four years later, he began attending the local al-Quds Mosque, popular with Islamist men. Atta was radicalized towards Islamism, either by meeting those men, or being directly contacted by an agent of bin Laden. He then became the ringleader of the Hamburg cell, a clandestine cell system of Islamic extremist terrorists who lived in the city prior to 9/11. Likely, the cell were likely planning their own jihadist activities in Russia when they met al-Qaeda's leadership, and then joined the organization in late 1999 to work on the details of al-Qaeda's redesigned hijacking plan.

Besides Atta, eleven men were members: Abdelghani Mzoudi, Ahmed Taleb, Mamoun Darkazanli, Marwan al-Shehhi, Mohammed Haydar Zammar, Mounir el-Motassadeq, Naamen Meziche, Ramzi bin al-Shibh, Said Bahaji, Zakariya Essabar, and Ziad Jarrah. Atta, al-Shehhi, and Jarrah were hijacker-pilots on 9/11. Like Atta, many of the members came to Hamburg for education, and were radicalized at the al-Quds Mosque—which was run by Darkazanli. Zammar had been in the Muslim Brotherhood in Syria, as well as a jihadist fighter in the Bosnian War (1992–1995), and a war in Afghanistan. Bahaji acted as the cell's computer expert, Essabar helped them tamper with and forge passports, and el-Motassadeq helped with logistics, paying some members' bills, such as the students' tuitions.

Over a few months in 1999, before most of them ever engaged in terrorist activities, the members watched footage of jihadists fighting in Chechnya, a region which is internationally recognized as a republic of Russia, but is populated by separatist Chechen groups, including Islamist militants. In the Second Chechen War (1999–2009), the Islamists waged defensive jihad against the Russian military. Watching the videos, the cell became motivated to join them in-person.

Hijackers and their collaborators

On 9/11, 19 members of al-Qaeda hijacked four commercial planes in the United States, and all 19 died as a result of their flights' respective crashes. During the planning of the attacks, Khalid Sheikh Mohammed was the third-in-command of al-Qaeda, as the head of its "military committee" which provided operational support to the hijackers. One of his roles was to help them arrange travel. He later recalled that al-Qaeda "had a large surplus of [members] willing to die as martyrs [for Islam]" by committing suicide attacks, and described a "department of martyrs" in the organization which consisted of only those people. Al-Qaeda's leaders chose the hijackers in 2000, looking for members who had special skills. Bin Laden selected al-Shehhi, Atta, bin al-Shibh, and Jarrah, because they were English speakers, educated, and by living in Germany, had experience in the West. Bin al-Shibh was eventually denied a U.S. visa, so he stayed in Hamburg, Furthermore, bin Attash took trips of various U.S.-based airlines to test their security.

American Airlines Flight 11

American Airlines Flight 11, which departed Logan International Airport in Boston for LAX, was crashed into 1 World Trade Center. The perpetrators were the hijacker-pilot Mohammed Atta, and four Saudis: Abdulaziz al-Omari, Satam al-Suqami, and brothers Wail and Waleed al-Shehri. During Flight 93's hijacking, the crew and passengers revolted against the terrorists, and tried to take back the plane's cockpit. This caused it to crash in a field in Stonycreek Township, Somerset County—rather than the hijackers' intended target. The target is unknown, but investigators presume it to have been either the U.S. Capitol or the White House. Jarrah moved from Lebanon to Hamburg in the 1990s, and there, he met al-Shehhi and Atta at the al-Quds Mosque. Al-Hawzani was from Al Bahah, and was recruited to train with al-Qaeda in Afghanistan while fighting in Chechnya. Al-Nami was from Asir. In 2000, he left his family's home to take the Hajj, Islamic pilgrimage to Mecca, and did not come back, as he was recruited to train in Afghanistan. Saeed dropped out of school when he joined the fight in Chechnya. Like others, he was recruited to go to Afghanistan during the war. This was the first time any hijacker entered the U.S. in preparation for the attacks. Some investigators suspect al-Bayoumi of involvement in 9/11, including by helping the pair open a bank account in the U.S. Ultimately, he was never charged. The 9/11 Commission Report claimed he was not an extremist; in contrast, former CIA analyst Gina Barrett claims that he was essential in the plot, as when he met al-Mihdhar and Nawaf, they spoke very little English, while he was fluent in it.

Mohamed Atta, Ramzi bin al-Shibh, and Ziad Jarrah were still in Afghanistan in January 2000. A videotape timestamped January 8, and released in 2006, shows them together with bin Laden at al-Qaeda's Tarnak Farms camp in the country. Later in January, after returning to Germany, Marwan al-Shehhi and Atta hid their time in Afghanistan from potential security officials at international airports by reporting their passports as stolen and receiving blank duplicates. Jarrah did the same in February. On May 18, Atta applied for and received a U.S. visa. Al-Shehhi arrived in the U.S. on the 29th. Authorities believed that Yemenis were more prone to overstaying visas. From around June to September 2000, al-Shehhi received five wire transfers from a sender or senders in the UAE: $4,790 USD while he was in Manhattan, and to his joint bank account with Atta at a SunTrust bank in Florida: $9,984, $9,485, $19,985, and then $69,985. In that same period, in Germany, bin al-Shibh wired unspecified amounts of money separately to Atta and al-Shehhi in Florida. At some point, he left San Diego for Arizona to refresh his piloting skills.

At the Ohio Pilot Store around March 19, Nawaf al-Hazmi purchased flight deck videos of Boeing 747 and 777 models.

On May 19, al-Suqami and Waleed al-Shehri flew from Fort Lauderdale, Florida, to Freeport, Bahamas, where they had made reservations at the Princess Resort. However, they lacked proper documentation to enter the country, and were stopped upon landing. They returned to Florida the same day, then rented a car.

Wail al-Shehri arrived in the U.S. in June. Sometime after, Jarrah rented a new apartment in Lauderdale-by-the-Sea, Florida, and al-Haznawi moved with him. Salem had a tourist visa. Al-Omari then likely stayed with several other hijackers in Paterson, New Jersey, before moving to his own place in Vero Beach, Florida, with his wife and three children. Atta purchased a knife in Zurich around July 8. In contrast, Atta complained to bin al-Shibh around this time about Atta's difficulty in getting through to Jarrah amid tensions between them over the viability of the plan. Atta feared he might withdraw from the plot completely. Jarrah did exit the conspiracy at one point, but then rejoined soon after; he might have done this twice. In July, Atta met bin al-Shibh in Spain to go over details of the plot, and make the final decision of what the hijackers' targets were. Bin al-Shibh told Atta that bin Laden wanted the attacks to happen as soon as possible. On July 25, Jarrah flew from the U.S. to Germany. Around August 17, Jarrah had a checkride in Fort Lauderdale. Around the 22nd, he purchased schematics of a Boeing 747 cockpit, as well as various GPS equipment, including an antenna. About three weeks before the attacks, the hijackers' targets were assigned to four teams. The U.S. Capitol was called "The Faculty of Law"; the Pentagon, "The Faculty of Fine Arts"; and the World Trade Center, "The Faculty of Town Planning".

The hijackers purchased their flight tickets in August and early September. On August 24, both al-Mihdhar and Moqed tried to purchase flight tickets from American Airlines online, but had technical difficulties in entering their address, and gave up. On the 27th, Nawaf and Salem al-Hazmi purchased tickets for Flight 77. On the 28th, Wail and Waleed purchased for Flight 11, and Atta purchased for himself and al-Omari on the same flight. On the 29th, Banihammad and Hamza al-Ghamdi purchased for Flight 175. The FBI claimed that Hamza also purchased for a "Flight 7950" from Los Angeles to San Francisco, although they did not give the projected date of the flight.

Over a few days in late August and early September, six of the hijackers stayed in Laurel, Maryland, at the Valencia and the Pin-Del Motels; it is unknown if this was to surveil the NSA's headquarters, which were a few miles away.

Reasoning for attacking on September 11

It is unknown why September 11 in specific was selected as the attack date. Al-Qaeda, in an act of symbolic terrorism, may have used numerology in choosing it. Before the attacks, the organization's internal name for the plot had been "Operation Holy Tuesday"; September 11, 2001, was a Tuesday. Otherwise, al-Qaeda may have been taking religious revenge for September 11, 1683, when the Muslim Ottoman Empire's militaristic expansion into Europe was ended by the Christian Holy Roman Empire at the Battle of Vienna. The Ottomans became permanently weakened, as did Islam's reach in Europe.

Early September 2001

In early September, Jarrah called his father and asked for money for flight training. His father gave him $2000 USD, which investigators believe did not pay for the training, but rather for tickets for Flight 93—for him, al-Nami, al-Haznawi, and Saeed al-Ghamdi. Wail and Waleed phoned American Airlines on September 3 to change their seat assignments for Flight 11, selecting different seats in first class on the other side of the aircraft, as they offered a direct view of the cockpit.

In the week before 9/11, al-Hawsawi received excess money from at least four hijackers. First, Banihammad's SunTrust account transferred about $8,055 USD to one of his own Dubai accounts that al-Hawsawi had access to. Al-Hawsawi then received $2,860 and $5,000 from Atta, $5,400 from al-Shehhi; and $5,000 from Waleed al-Shehri. He also received a Fed-Ex package of unknown contents from Atta. On 9/11, about $16,384 was deposited into al-Hawsawi's own Dubai account, and al-Hawsawi transferred about $6,534 from Banihammad's Dubai account into his own—then withdrew almost all the remaining money on Banihammad's account, about $1,631, in cash from an ATM. On the 9th, Jarrah called his family, and told them he would be at his cousin's wedding on the 22nd. Just before the attacks, he possibly set up a large mock cockpit made of cardboard boxes in his apartment.

Morning of September 11, 2001

Between 4:45 to 6:45 a.m. ET on September 11, 2001, Ziad Jarrah made five phone calls to numbers in Lebanon, one in France, and one in Germany—the latter to his girlfriend, Aysel Şengün. He made a similar call to Mohamed Atta, but not to the other hijacker-pilot, Hani Hanjour. Atta and Abdulaziz al-Omari started the day in Portland, Maine. At 6 a.m., they boarded a Colgan Air flight departing Portland International Jetport for Boston, where they met the three other American Airlines Flight 11 hijackers at Logan International Airport. thumb|280x280px|Nawaf and Salem al-Hazmi at [[Dulles International Airport in Virginia on 9/11]]

The three other groups entered their respective airports: United Airlines Flight 175 at Logan, the American Airlines Flight 77 group at Dulles International Airport, and the United Airlines Flight 93 group at Newark International Airport. In violation of FAA policy, the security agents likely did not check the carry-on bags of those who set off alarms. The hijackers' bags likely contained stabbing instruments such as box cutters, which were used in the hijackings. However, even if the agents did check the bags, such instruments had been allowed by the FAA before 9/11 to be carried onboard.

The flights took off between 7:59 and 8:42 a.m. On Flight 93, at least one of the four terrorists brought onboard a pamphlet instructing them on how to hijack the plane. It began: "Embrace the will to die and renew allegiance. Familiarize yourself with the plan well from every aspect, and anticipate the reaction and resistance from the enemy." Twice during Flight 93's hijacking, Jarrah attempted to radio the cabin that a bomb was onboard by speaking into a voice recorder in the cockpit, but unbeknownst to him, his audio instead went to air traffic controllers in Cleveland. The four crashes happened at 8:46 (Flight 11 into 1 World Trade Center), 9:03 (Flight 175 into 2 World Trade Center), 9:37 (Flight 77 into the Pentagon), and 10:03 (Flight 93 in Pennsylvania). When Said Bahaji joined the Hamburg cell, German authorities were investigating him for associating with Zammar. The investigation was closed, as they could not find evidence of the pair committing crimes. Upon his first fatwa in August, the FBI and the U.S. Attorney for the Southern District of New York opened a criminal file on him under the charge of seditious conspiracy. In December 1998, after bin Laden announced upcoming attacks against the U.S., the CIA's Counterterrorist Center reported to president Bill Clinton that al-Qaeda was preparing such an attack, involving trained personnel hijacking airliners.

In the months before 9/11, U.S. federal agencies received numerous warnings from their employees about the attack. CIA director George Tenet later claimed that, in response to those circulating in his agency, he tried to get more employees paying attention to al-Qaeda's plan, but failed. After 9/11, the FBI alleged that the CIA did not notify them about al-Qaeda's Kuala Lampur summit after its details were intercepted in 1999. The CIA responded by claiming they did email the FBI; the latter then stated they had no records of receiving such an email. On August 6, president George W. Bush's daily brief was titled "Bin Ladin Determined to Strike in U.S." [sic]. The NSA received at least 33 warnings about al-Qaeda's plan in the months before the attacks. Director Michael Hayden later testified that, days before 9/11, they received one that said an attack would happen on the 11th, but its wording was not translated until the 12th. It did not mention the attack's type, specific location, or time of day. At 9:52 a.m., the NSA intercepted a phone call between a known associate of bin Laden in Afghanistan, and someone in the Republic of Georgia, the former announcing that he had heard "good news", and that another target was still to be hit. Around 3:30 p.m., Bush convened a meeting of U.S. intelligence officials. George Tenet stated that he was very certain that bin Laden and his associates were the perpetrators, mentioning that U.S. intelligence had checked the manifest of Flight 77, and found three names of known al-Qaeda members. First involving 70 people, the FBI conducted 180,000 interviews and reviewed millions of pages of documents, and just within the first few months after the attacks, looked into more than 250,000 leads. Thousands of agents were dispatched to other countries for field research. The FBI checked daily reports from CIA and military intelligence officials, as well as reports of interrogations at U.S. facilities across the world. Thousands of leads were useless, leading FBI Director Robert Mueller to claim his agents were "trying to find the needle in the haystack". Nonetheless, by 2004, other investigative panels within the U.S. government accused PENTTBOM of not being thorough enough. In 2002, the U.S. Senate and House's intelligence committees investigated the attacks generally, via the Joint Inquiry into Intelligence Community Activities before and after the Terrorist Attacks of September 11, 2001. 80 people were full-time members, including staff. The Commission held reoccurring public hearings on the investigation's progress. Saudi Arabia has denied this.

Prior to 9/11—while unaware of the royals' potential connection to al-Qaeda's plot—multiple U.S. intelligence agencies investigated possible financial ties between them and bin Laden. In June 2001, a "high-placed member of a U.S. intelligence agency" told the BBC that after George W. Bush was inaugurated as president that January, his administration forced the agencies to stop looking into any connections. In October 2001, the U.S. officially identified him as one of bin Laden's primary financiers. They discovered that he had led the Muwafaq Foundation, an arm of al-Qaeda. Ptech's other higher-ups were also revealed to be connected to Islamic extremism.

In 2002, 28 pages of the Joint Inquiry into Intelligence Community Activities' final report were not released to the public, at the order of the Bush administration. Bipartisan congressional leaders criticized the decision.

thumb|246x246px|Prince [[Bandar bin Sultan Al Saud|Bandar]]

From around 1999 to 2002, a bank account under the name of Saudi Princess Haifa, the wife of then-Saudi ambassador to the U.S., Prince Bandar, sent thousands of dollars USD to Majida Dwaikat, the wife of a man named Osama Basnan—Khalid al-Mihdhar and Nawaf al-Hazmi's friend while they were in San Diego. This information was leaked in November 2002, sourced from an FBI investigation. Time subsequently wrote that the leak "[has] thrown the FBI and Justice Department on the defensive", as both denied that the revelation was evident of Saudi funding of al-Qaeda. In San Diego, Al-Mihdhar and al-Hazmi may also have been connected to al-Qaeda via Omar al-Bayoumi, who some investigators suspect was a Saudi intelligence agent. In the aforementioned 2001 search of his U.K. apartment, investigators found an address book with contact details of Saudi government officials. In 2024, the FBI stated that al-Bayoumi taped his 1999 Washington, D.C. video while standing next to two Saudi diplomats who had ties to al-Qaeda at that time. In a statement, the Saudi government noted that Moussaoui's own lawyers presented evidence of him being mentally incompetent during the trial.

Into Pakistani involvement

In October 2001, U.S. authorities were reported as seeking the removal of Mahmud Ahmed as head of Pakistan's Inter-Services Intelligence agency (ISI), as the FBI had recently found that Ahmed Omar Saeed Sheikh wired the aforementioned $100,000 to Mohamed Atta at Mahmud's request. The FBI determined this after looking into the cell phone company Sheikh had been subscribed to. The allegation had severe implications for the privacy of U.S. intelligence operations prior to 9/11, as Ahmed had had a professional relationship with numerous American officials, including Bush's vice president Dick Cheney. Soon after the allegation was publicized, he resigned as head of the ISI.

Into hijackers' Maine and Nevada trips

thumb|280x280px|Al-Omari (in white, center) and Atta (in blue) at [[Portland International Jetport in Maine on 9/11]]

Al-Omari and Atta's presence in Portland, Maine, on September 10 and 11 was publicized upon the attacks; by the end of that week, many of the city's residents told investigators they had seen Atta and other hijackers there the previous summer, which could imply the city was home to a terrorist cell. The FBI investigated the claims, and found them unsubstantiated. Portland Police Chief Michael Chitwood also investigated them; he could not find any evidence of a cell, yet his investigation was ended prematurely, as "I was told I needed to stop investigating and let the FBI handle it." As of 2020, why the hijackers went to Las Vegas several times in uncertain, At those places, the U.S. deployed torture methods, officially named "enhanced interrogation techniques", against prisoners, sometimes in an attempt to get info about 9/11, or al-Qaeda generally. Research has found torture does not work as an interrogation technique, and often leads to the victims giving false info. The FBI used the U.S. government's reports of interrogations at Guantanamo in the PENTTBOM investigation. He was transferred to Guantanamo, where he was also tortured. He is charged at the camp's court with planning 9/11, and intends to defend himself from the charges, despite admitting to his involvement. In a trial that started in 2012 and continued for years, he was jointly prosecuted with Mohammed, Ammar al-Baluchi, Mustafa al-Hawsawi, and Walid bin Attash. In 2023, the court found bin al-Shibh was not mentally able to defend himself in a joint case due to psychological trauma from torture. He was moved to a separate, tentative trial. Zammar was imprisoned there until 2014, when he was released in a prisoner exchange between Syria and Islamic militant group Ahrar al-Sham. He then joined the Islamic State militant organization as they were invading Syria, and did numerous jobs for them. In 2018, he was captured in Syria, and imprisoned there again.

Mounir el-Motassadeq

Mounir el-Motassadeq was arrested in Germany shortly after 9/11.

Abdelghani Mzoudi

Abdelghani Mzoudi was arrested in Germany, and trialed over his role in the cell. Like with el-Motassadeq, the U.S. did not allow bin al-Shibh and Mohammed to testify in his trial. He was acquitted in 2004, as without the testimonies, prosecutors did not have a strong enough case against him. In 2005, he was also deported to Morocco.

Mamoun Darkazanli

Mamoun Darkazanli was not arrested for being in the Hamburg cell. In 2004, Spain issued a European Union (EU) warrant for his arrest over alleged involved in the Madrid train bombings earlier that year. An attempt to extradite Darkazanli back to Spain was blocked by a judge in Germany, and then German authorities found that the EU arrest warrant violated Germany's constitution, so in 2005, he was freed. In 2010, Sidiqi was captured in Afghanistan, and interrogated at Bagram prison. According to the U.S., he told them that he was involved in al-Qaeda's plot to conduct terrorist attacks across Europe.

Said Bahaji, Zakariya Essabar, and Naamen Meziche

Shortly after 9/11, Germany stated that likely, Said Bahaji and Zakariya Essabar had recently moved to Pakistan or Afghanistan. Naamen Meziche is known to have left Germany for Afghanistan on or around the 11th. As of 2011, he is rumored to have died there, while Essabar's whereabouts are still unknown. in 2009, Pakistan took back a Taliban-controlled town, and found there a supposed Pakistani passport issued to Bahaji. Sidiqi allegedly claimed to have met Bahaji at an Islamic militant camp in Pakistan around 2009. However, as of 2025, Germany still has an active arrest warrant for him.

Suspects

thumb|253x253px|[[Ammar al-Baluchi being forced to be nude, likely at a CIA black site in Romania in 2004]]

Ammar al-Baluchi

Ammar al-Baluchi was captured in 2003. For three years at CIA black sites, he was subject to 1,100 interrogations, with some questions being provided by the FBI. He was regularly beaten, forced to be nude, and allegedly, received brain damage from being repeatedly thrown at a wall once. In one instance, al-Baluchi was simultaneously waterboarded, forced to be nude, and forced to stand for 82 hours, causing sleep deprivation. Slahi had trained with al-Qaeda in 1991, but claims he soon severed ties with them." Soon after 9/11, he was captured by the U.S., and sent to Guantanamo,