What is the main purpose of warning areas in the NAS?

The main purpose of warning areas in the National Airspace System (NAS) is to warn nonparticipating aircraft of potential hazards. These areas are designated to notify pilots that activities within them may pose a risk to safety, such as military training exercises or other operations that could involve activities like live munitions testing or aerial maneuvers. While flights may be conducted within these areas, pilots are advised to exercise caution, as there may be various hazards present that could interfere with their safety.

In contrast, the other options do not accurately reflect the purpose of warning areas. They do not fully prohibit flight over these regions; instead, they serve as cautionary zones. They also do not indicate safe zones for landing or solely restrict military aircraft, as the intent is to communicate potential dangers to all nonparticipating aircraft, thus ensuring overall safety in the airspace.