How is hostile surveillance best defined?

Hostile surveillance is best defined as surveillance conducted by an adversary that seeks to gather information or assess the vulnerabilities of a target, often with the intention of planning illegal or harmful actions. This type of surveillance is characterized by its secretive nature, as the observer aims to remain unnoticed while collecting valuable data on organizations, individuals, or activities that they may intend to exploit or attack.

In contrast, the other definitions do not capture the essence of hostility associated with such surveillance. Surveillance conducted by law enforcement occurs under legal authority with a protective or investigative purpose, and ongoing monitoring by a friendly entity implies cooperation and support rather than adversarial intentions. Observation intended for public awareness does not involve covert tactics typically associated with hostile surveillance, as it is often part of transparent activities meant to inform or engage the public.