Spooks are a group of carefully selected, highly trained technicians that conduct intelligence operations in absolute secrecy. The title Spook probably originated in the late 1950s or early 1960s.
Predominantly enlisted communication technicians, later known as cryptologic technicians (CTs) and special duty (cryptologic) officers, these technicians serve as direct support operators and officers to support national, theater and tactical intelligence requirements.
Serving on a variety of tactical platforms, these technicians disappear in the shadows of highly secured areas. They only reappear into the light to eat or go to hit their racks; some, however, sleep in their spaces where they work.
Once mission objectives were satisfied these technicians remove their tech-kits, specialized equipment and quietly disembark, leaving the workspace as they found it. To the regular navy these technicians were a mystery, like ghosts.