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.
The term stealth refers both to a broad set of tactics aimed at providing and preserving the element of surprise and reducing enemy resistance.
Some operations may have both clandestine and covert aspects, such as the use of concealed remote sensors or human observers to direct artillery attacks and airstrikes.
In World War II, targets found through cryptanalysis of radio communication were attacked only if there had been aerial reconnaissance in the area, or, in the case of the shootdown of Admiral Isoroku Yamamoto, where the sighting could be attributed to the Coastwatchers.
During the Vietnam War, trucks attacked on the Ho Chi Minh trail were completely unaware of some sensors, such as the airborne Black Crow device that sensed their ignition.