What term is used for training that takes place covertly at the level of a terrorist cell?

The term "internal training" is used to refer to training that occurs covertly within a terrorist cell. This type of training is typically designed to strengthen the capabilities of members of the cell, focusing on skills that are only relevant within the specific group. Internal training is crucial for maintaining operational security and fostering loyalty among members, as it takes place away from public view and often employs methods that are unique to that particular organization.

In this context, internal training can include indoctrination tactics, operational procedures, tactical skills, and even ideological education that align with the group's objectives. The secrecy surrounding these training sessions adds to their effectiveness, as members are less exposed to detection by authorities and can focus on developing skills that will further the group's aims without outside interference.

In contrast, the other terms would not accurately describe this kind of training. External training typically refers to training received outside the organization, formal training suggests a structured educational approach typically recognized by relevant authorities, and cooperative training implies a partnership with other organizations, which does not align with the covert nature of activities within a terrorist cell.