THREATCON Delta is declared when what occurs?

THREATCON Delta is declared in response to an immediate and specific threat level. This level indicates that a terrorist attack has either occurred or is imminent. Declaring THREATCON Delta signifies that a situation requires the highest level of readiness and vigilance, as there is a clear and present danger to personnel, assets, or operations.

In this context, the declaration serves to mobilize resources, enhance security measures, and raise awareness among all personnel to ensure they are prepared to respond effectively. It is a reactive measure that reflects the seriousness of the threat, necessitating comprehensive protective actions.

The other options do not align with the definition of THREATCON Delta. For example, stating that no known threats exist would suggest a state of normal operations, which contradicts the intent of Delta readiness. Increased intelligence on terrorist likelihood might correlate more closely with THREATCON Bravo, which indicates a heightened level of threat but not one that is immediate. General alertness required would be a characteristic associated with lower THREATCON levels that do not demand the urgent actions necessitated by a specific attack or risk.