Hamburg cell

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.

Mohamed Atta's apartment on Marien Street in Hamburg, where the September 11 attacks were planned

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.

The general plan for the attacks was developed by al-Qaeda officials Osama bin Laden and Khalid Sheikh Mohammed, and the cell worked out its details in Atta's apartment. Out of the members who were still alive after September 11, three of them—Bahaji, Essabar, and Meziche—likely escaped to Afghanistan and Pakistan. The rest were arrested for their involvement; most were imprisoned, while Mzoudi was acquitted, and bin al-Shibh and Darkazanli never faced full trials.

Background

Further information: September 11 attacks and Hijackers in the September 11 attacks

United Airlines Flight 175 crashing into 2 World Trade Center in New York City, while 1 World Trade Center is damaged from the impact of American Airlines Flight 11

In the September 11 terrorist attacks in 2001, 19 men who were members of the Islamist militant organization al-Qaeda hijacked four American commercial flights in an attempt to crash them into important landmarks in the country.^[1][2] American Airlines Flight 11 and United Airlines Flight 175 were crashed into 1 and 2 World Trade Center in New York City. Both towers soon collapsed as a result of the damage. American Airlines Flight 77 crashed into the Pentagon near Washington D.C.^[2] United Airlines Flight 93 crashed in a field in Stonycreek Township, Pennsylvania; the hijackers had redirected it towards Washington D.C., likely aiming for the U.S. Capitol Building, but the surviving passengers and crew revolted against the hijackers mid-flight, likely causing the hijackers to send the plane downwards.^[2][3] 2,977 people were killed in the attacks.^[2]

Osama bin Laden, a fugitive of Saudi Arabia, founded al-Qaeda.^[2][4] The organization funded the September 11 attacks as revenge against the United States for the country's military presence in the Middle East, involvement in the Gulf War (1990-1991), and support of Israel.^[4] While bin Laden is considered the main perpetrator of the September 11 attacks,^[2] Khalid Sheikh Mohammed was the principal designer of the attack plan.^[4] The latter led al-Qaeda's propaganda operations from 1999 to 2001, and gave details on the planning after he was captured in Pakistan in 2003.^[4][5]

In 1993, a group of al-Qaeda members led by Ramzi Yousef, Mohammed's nephew, set off a large bomb underneath the World Trade Center (WTC).^[6][7] He was testing a plan his uncle had been developing, known as the Bojinka plot; eleven planes flying from Asia to the U.S. would be hijacked over the Pacific, and then used to attack American targets, as well as assassinate Pope John Paul II. It never came to fruition, but it evolved into the plan for the September 11 attacks.^[5][8] In 1994, Yousef bombed Philippine Airlines Flight 434; for this and the WTC bombing, he was arrested in 1995.^[6] Mohammed continued with his plan. In 1996, he brought up the idea of flying planes into buildings to bin Laden, who was living in Afghanistan. Mohammed said the number of planes used would be ten, which bin Laden said was too elaborate.^[8] They started working on a redesigned plan in spring 1999.^[9]

History

Radicalization of the cell members

bin Laden and Mohammed's plan was worked on in Hamburg, Germany, by the "Hamburg cell": a clandestine cell system of men associated with the organization.^[10][11] In 2002, while under arrest for being a member of the cell, Ramzi bin al-Shibh issued a statement through his lawyer stating the only other members were Mohamed Atta, Marwan al-Shehhi, and Ziad Jarrah. The latter three hijacked three separate planes in the attacks, and were the ones in their respective groups who flew the planes after their hijackings. Atta piloted Flight 11, al-Shehhi piloted Flight 175, and Jarrah piloted Flight 93.^[11][12] Hani Hanjour, the pilot of Flight 77, was not part of the cell.^[13] Despite bin al-Shibh's statement, law enforcement officials from Germany, the U.S., and the United Nations describe many others as members.^[11][12]

Mohamed Atta, the leader of the cell

The ringleader was Atta, an Egyptian-born architect who enrolled in university at Hamburg in 1992. He decided to study urban planning.^[14][15] In 1996, he began attending the local al-Quds Mosque, which had Muslim visitors from around the world.^[14] It was ran by Mamoun Darkazanli. At some point before September 11, the U.S. became aware that Darkazanli was associated with al-Qaeda, and asked Germany to stop him. Germany, however, did not, as they had no laws at the time prohibiting being part of a foreign terrorist organization.^[11] At the mosque, many young men were associated with Islamism, and enforced Islamic morality in the behavior of the other visitors.^[9] Atta was radicalized during his visits, either by meeting the other worshippers, or being directly contacted by an agent of bin Laden.^[11]

Atta soon met four future members of the cell: al-Shehhi, Jarrah, Said Bahaji, and Mounir el-Motassadeq.^{[10][11][16][9]} al-Shehhi was a devoted Muslim from the United Arab Emirates, and was studying in Hamburg via a scholarship program by the Emirati military.^[11] Jarrah was from a Sunni Muslim family, but was mostly secular when he arrived to study in Hamburg as well.^[11][9] Both of them arrived in 1996.^[11] Said Bahaji was a Moroccan-born man who moved to Germany, and served five months in the German Army before being discharged for medical reasons.^[11] el-Motassadeq was also from Morocco.^[17]

Zakariya Essabar moved to Germany in 1997, and to Hamburg in 1998, he where began studies. After repeated visits to the mosque, Jarrah started observing Islamic rules, and multiple members—including him, al-Shehhi, and Essabar—became radicalized like Atta.^[11][14][9] Ramzi bin al-Shibh was born in Pakistan, raised in Kuwait, and was a Yemeni national at the time he met the cell members.^[11] He maintained his Germany residency status by continuously enrolling into classes in Hamburg, but rarely showed up to them.^[9] Darkazanli, Abdelghani Mzoudi and Naamen Meziche also joined the cell.^[18]

The interior of al-Quds Mosque in 2009

Initial activities

By the time Bahaji joined the Hamburg cell, he was under investigation by German intelligence for associating with a radical Muslim cleric named Mohammed Haydar Zammar, but the case was closed due to a lack of evidence of crimes.^[11] Zammar was an auto mechanic who had been a jihadist fighter in Afghanistan and Bosnia, as well as a member of the Muslim Brotherhood in Syria. He was still interested in violent jihad when the cell was formed.^[9][18][19] Bahaji and Zammar have both been described as the one who brought all the members together.^[9][20] Zammar was unknowingly being surveilled by the Federal Criminal Police Office and the Central Intelligence Agency (CIA), but their efforts were not thorough enough to catch the cell planning the September 11 attacks.^[9]

De facto control of Chechnya and surrounding areas before the Second Chechen War, showing Russia's control (red), the unrecognized Chechen Republic of Ichkeria (green), and the Islamists inside it (grey)

Over a few months in 1999, the cell members watched footage of jihadists fighting wars in Afghanistan, Bosnia, and Chechnya. The latter region was internationally recognized as a republic of Russia, but was populated by separatist groups. A military of the unrecognized breakaway state named the Chechen Republic of Ichkeria, as well as Islamist Chechen militants, rebelled against Russia during the Second Chechen War (1999-2009). Watching the Islamists fight, the cell became motivated to join them in-person.^{[9][19][21][22]}

All the cell members stopped contacting their families, except Jarrah. His family tried to stop him from being radicalized, and he may have had doubts about participating in the attack.^[11] No women were present at Bahaji's wedding at the al-Quds Mosque in October 1999—not even his bride. It was attended by Atta, al-Shehhi, Jarrah, and bin al-Shibh; the latter was the event's principal speaker, and he urged the guests to fight against Jews.^[23][24]

1999 train meeting and Duisburg visit

After September 11, German and American authorities had contradictory findings over when the Hamburg cell decided to attack the U.S. In late 1999, after the cell decided to fight in Chechnya, they boarded a train going east. According to the U.S.' 9/11 Commission, apparently by chance, an al-Qaeda member named Khalid al-Masri was onboard the train at the same time, and he met the cell, then convinced them to join his organization; beforehand, they apparently had no intentions of attacking the U.S. They then traveled to Afghanistan and met bin Laden. The commission's findings contrasted Germany's understanding that the cell came up with the plan independently of al-Qaeda. Reacting to the U.S.' findings, German intelligence official Manfred Murck said it helped him understand why Germany's pre-September 11 surveillance of domestic Islamic extremists did not catch the plan; it was not made in Germany. The U.S. claimed no connection could be made between the cell and al-Qaeda beforehand, and that their conclusion was built off testimony bin al-Shibh gave after he was captured.^[19]

Mohamedou Ould Slahi, who allegedly introduced the cell to al-Qaeda

The U.S. found that Mohamedou Ould Slahi also played a role in connecting the groups. Slahi was a Mauritanian who ran an import-export business in Duisburg, Germany. His cousin knew bin Laden. At the time, German and American intelligence knew of him, and that he was with al-Qaeda, but not that he was living in Germany. On the train, al-Masri supposedly asked the cell to visit him. After traveling to Duisburg, Slahi warned them it was hard to cross the border into Chechnya. He said they should instead go to Pakistan, to rendezvous with al-Qaeda operatives who could get them across the country's border with Afghanistan. The members would then meet bin Laden and the other higher-ups in al-Qaeda.^[9][19]

1999—2000 Afghanistan visit

At the time, al-Qaeda was allowed by the Taliban, Afghanistan's Islamic fundamentalist government, to use the country as its base of operations.^[25] Shortly after the meeting with Slahi, Atta, al-Shehhi, bin al-Shibh, and Jarrah entered Afghanistan separately to meet with the organization's leadership. The four were trained to be jihadist terrorists, and briefed on the plan to hijack American airliners.^[9][19]

Some of the members eventually met up in Afghanistan. Raw footage with the timestamp of January 8, 2000, shows multiple people watching bin Laden speak at al-Qaeda's Tarnak Farms training base in the country. They include Atta; bin al-Shibh; Jarrah; al-Qaeda officers Abu Faraj al-Libbi and Saif al Adel; and Fahid Mohammed Ally Msalam, who was wanted for participating in the organization's 1998 bombing of U.S. embassies in East Africa. Similar footage timestamped January 18, shows Atta and Jarrah stating their last wills and testaments, and discussing unspecified sheets of paper on the floor next to them. The former recording was likely to be used in an official al-Qaeda propaganda video. Both recordings were released in 2006; subsequent attempts by authorities to lip read Atta and Jarrah's discussion of the papers were futile.^[26] The cell members who visited Afghanistan eventually returned to Hamburg.^[9][19]

Planning the hijacking attacks

Further information: Planning of the September 11 attacks

Ramzi bin al-Shibh was a liaison between the cell and al-Qaeda

At different times between November 1998 and July 1999, Bahaji, bin al-Shibh, and Essabar lived with Atta in his apartment on Marien Street in Hamburg. There, the cell began working out the details of the hijacking plan.^[10][11][27] Investigators disagree if Jarrah ever lived there.^[27][28] bin al-Shibh had been selected by al-Qaeda's higher-ups to be a hijacker, and he made a video where he proclaimed he was going to be a martyr.^[11] However, he was unable to get an American travel visa, so he instead acted as a liaison between the cell and al-Qaeda's leadership, telling the members what their targets were, and notifying them of wire transfers from the higher-ups.^[10][11] el-Motassadeq helped with logistics, and paid some members' bills, such as the students' tuitions.^[29][30] Bahaji was the cell's computer expert, and Essabar helped them tamper with and forge passports.^[11]

In January 2000, to hide their time in Afghanistan from security officials at international airports, Atta and al-Shehhi reported their passports as stolen and received blank duplicates; Jarrah did the same in February.^[14] The three men then left Germany for the U.S. and enrolled at Huffman Aviation, a flight school in Venice, Florida.^[11] el-Motassadeq kept paying the rent on their homes in Germany to make it look like they planned to come back.^[29][30] Bin al-Shibh helped the three men find the flight school, and sent them $120,000 USD to pay the expenses of living in the U.S. and going to the school. Essabar may have gone to Afghanistan shortly before September 11 to tell the leaders of al-Qaeda the date of the attacks.^[11]

Members

The following is a list of all cell members described by officials in Germany, the U.S. and the U.N., detailing what happened to them during or after the attacks, and what consensus says about their status as a member:

Cell members according to Germany, the U.S., and U.N.

Name	Fate or current status	Consensus as to participation	Ref.
Mohamed Atta	Died as the hijacker pilot of American Airlines Flight 11	Confirmed	[12][11][18]
Marwan al-Shehhi	Died as the hijacker pilot of United Airlines Flight 175	Confirmed	[12][11][18]
Ziad Jarrah	Died as the hijacker pilot of United Airlines Flight 93	Confirmed	[12][11][18]
Ramzi bin al-Shibh	Captured by Pakistan and given to the U.S. in 2002, upon which he admitted to being a cell member Held in CIA custody until transferred to the Guantanamo Bay detention camp in Cuba in 2006 First appeared in court at Guantanamo in 2008 on charges of planning 9/11 In 2012, was put on trial, which continued for the next 11 years; the trial and his defense against the charges were happening in spite of the admission In CIA custody and at Guantanamo, underwent years of torture that—as his lawyers successfully argued in 2023—rendered him mentally unable to defend himself in the trial	Confirmed	[12][11][31][32][33][18]
Abdelghani Mzoudi	Arrested by Germany after 9/11, put on trial, and was acquitted in 2004 Deported to Morocco in 2005	Described by authorities as a member, but was acquitted in trial Not described by Ramzi bin al-Shibh	[12][11][34][18]
Mamoun Darkazanli	Arrested by Germany for allegedly participating in the 2004 Madrid bombings An extradition back to Spain was blocked by a judge Released in Germany in 2005 for multiple legal reasons	Described by authorities as a member Not described by Ramzi bin al-Shibh	[12][11][35][18]
Mohammed Haydar Zammar	Arrested by Morocco after 9/11 and extradited to Syria Released in 2013 as part of a prisoner exchange between Syria and militant organization Ahrar al-Sham Joined the Islamic State militant organization soon after, and was captured in 2018 Imprisoned in Syria again in 2018	Described by authorities as a member Not described by Ramzi bin al-Shibh	[12][36][37][38][39][40][9][18]
Mounir el-Motassadeq	Convicted in Germany in 2006 for planning 9/11 Imprisoned from 2007 to 2018 Deported to Morocco in 2018	Maintains that while he associated with al-Qaeda during the cell's existence, he was not a part of the planning of 9/11 Described by authorities as a member, but not by Ramzi bin al-Shibh	[12][16][30][29][41][42][18]
Naamen Meziche	Left Germany for Afghanistan Possibly died in Pakistan near the Afghanistan border	Described by authorities as a member Not described by Ramzi bin al-Shibh	[18]
Said Bahaji	Possibly fled Germany to Pakistan on September 3, 2001, after hearing that the 9/11 attacks were imminent During the Afghanistan–Pakistan border skirmishes in 2009, Pakistan cleared out a town that had been controlled by the Taliban, and found a supposed Pakistani passport of his which stated he entered the country on September 4, 2001 Died at the border in 2013, according to the U.N. Security Council The German Federal Criminal Police Office still has an active arrest warrant for him as of 2025	Described by authorities as a member Not described by Ramzi bin al-Shibh	[12][11][43][44][45][18]
Zakariya Essabar	At large as of 2010 Possibly traveled to Afghanistan shortly before 9/11 to communicate with al-Qaeda	Described by authorities as a member Not described by Ramzi bin al-Shibh	[12][11][46][18]

In popular culture

The film Hamburg Cell is a docudrama on the planning and execution of the attacks. A co-production between Channel 4 in the UK and CBC in Canada, it was shown in the UK during September 2004, amid criticism that this was too close to the anniversary of the attack. Using computer-generated imagery, the film's producers were able to show the twin towers of the World Trade Center, before the attack, in the background. Jarrah is featured calling his girlfriend, Aysel Sengün, from a public telephone at the airport, repeating the words 'I love you' over and over.

See also

• Planning of the September 11 attacks
• Brussels cell