Talk:Sleeper Agent/@comment-10502460-20190615042223

Sleeper agents are a real thing. It refers to refer to any human asset who is ordered to live within the infiltrated population and lay low without doing anything unless and until further orders are given or a certain situation arises.

What you're thinking of is what TV tropes refers to as a "Manchurian Agent," which are sleeper agents who don't know they are sleeper agents and can only be activated by a specific trigger, like you said. These are the kind that are only known to exist in fiction.