sleeper agent

A sleeper agent is a person who is secretly trained or embedded by an organization, often a government or intelligence agency, to carry out covert missions. They typically live normal lives without suspicion until activated by a specific signal or event, at which point they carry out tasks such as espionage, sabotage, or gathering information. The concept relies on the agent's ability to remain hidden and inactive for long periods, only acting when instructed, making them difficult to detect and neutralize beforehand.