Which tactic involves the gathering of intelligence on an enemy's activities?

Surveillance is the tactic that involves the systematic gathering of intelligence on an enemy's activities. This process allows forces to monitor the movements, behaviors, and operations of potential threats without direct confrontation. Through surveillance, various methods such as visual observation, electronic monitoring, and reconnaissance are employed to collect crucial information that can inform strategic decisions and enhance operational readiness.

The importance of surveillance in military operations cannot be overstated, as it provides insights into enemy capabilities and intentions, ultimately improving situational awareness. This intelligence is vital for planning and executing missions effectively, helping prevent unexpected attacks and ensuring the safety of personnel.

Other tactics mentioned, such as assassination, negotiations, and intervention, serve different purposes and focus on direct actions rather than the intelligence-gathering aspect characteristic of surveillance.