What is a sleeper cell?

Sleeper cells are covert groups or individuals who remain inactive within a target country or organization until they are activated to carry out a mission, often related to espionage, terrorism, or sabotage. These cells are usually well-integrated into the community and can operate undetected for years. When activated, members may engage in activities like intelligence gathering, planning attacks, or providing support to other operatives. The concept is widely used in intelligence and counterterrorism operations, and detecting sleeper cells is a significant challenge for security agencies.