Final answer:
The two key elements in civil disturbance planning are implementing civil defense and emergency preparedness measures, including anti-terrorism legislation, and ensuring the resilience of critical national infrastructure.
Step-by-step explanation:
The two key elements in civil disturbance planning are implementing civil defense and emergency preparedness measures, which include anti-terrorism legislation, and ensuring the resilience of a critical national infrastructure. The first element focuses on preparing laws and systems that aim to protect the public and prevent disruptions, such as terrorist acts.
The second key element concentrates on ensuring that vital systems such as power grids, water supply, and communication networks remain robust and capable of recovering quickly from any interruptions or attacks. These elements are critical in maintaining safety and order during civil disturbances, as well as preserving the functionality of essential services that support societal well-being and security.