A clandestine operation is an intelligence or military operation carried out in such a way that the operation goes unnoticed by the general population or specific ‘enemy’ forces. The US Department of Defense Dictionary of Military and Associated Terms defines “clandestine operation” as “An operation sponsored or conducted by governmental departments or agencies in such a way as to assure secrecy or concealment. A clandestine operation differs from a covert operation in that emphasis is placed on concealment of the operation rather than on concealment of the identity of the sponsor.
The bulk of clandestine operations are related to the gathering of intelligence, typically by both people and by hidden sensors. Placement of underwater or land-based communications cable taps, cameras, microphones, traffic sensors, monitors such as sniffers, and similar systems require that the mission go undetected and unsuspected.