Clandestine cell system in the context of "French Resistance"

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.

The Communist Party of Germany/Marxists–Leninists (German: Kommunistische Partei Deutschlands/Marxisten-Leninisten, KPD/ML) was a clandestine communist party active in both East and West Germany during the Cold War. It was founded in 1968 by former Communist Party of Germany (KPD) official Ernst Aust, who subsequently became the party's chairman. As an anti-revisionist party, the KPD/ML upheld the legacy of Soviet premier Joseph Stalin and supported China under Mao Zedong and later Albania under Enver Hoxha after the Sino-Albanian split. At its peak in the mid-1970s, the party claimed a membership of around 800.

The party published a periodical named Roter Morgen (transl. "Red Morning"). Former members of the party continued to publish the newspaper until December 2011.

Clandestine human intelligence is intelligence collected from human sources (HUMINT) using clandestine espionage methods. These sources consist of people working in a variety of roles within the intelligence community. Examples include the quintessential spy (known by professionals as an asset or agent), who collects intelligence; couriers and related personnel, who handle an intelligence organization's (ideally) secure communications; and support personnel, such as access agents, who may arrange the contact between the potential spy and the case officer who recruits them. The recruiter and supervising agent may not necessarily be the same individual. Large espionage networks may be composed of multiple levels of spies, support personnel, and supervisors. Espionage networks are typically organized as a cell system, in which each clandestine operator knows only the people in his own cell, perhaps the external case officer, and an emergency method (which may not necessarily involve another person) to contact higher levels if the case officer or cell leader is captured, but has no knowledge of people in other cells. This cellular organization is a form of compartmentalisation, which is an important tactic for controlling access to information, used in order to diminish the risk of discovery of the network or the release of sensitive information.