- Denial Measures taken to prevent unauthorized access or actions (e.g., locks, firewalls). - Detection Measures to identify that an unauthorized action or event has occurred or is occurring (e.g., alarms, surveillance systems). - Deterrence Measures aimed at discouraging potential adversaries from attempting an unauthorized action (e.g., visible security presence, warnings). - Destruction (4) is a consequence of an event or an active measure against a threat, not typically considered a core principle of security design or planning in the same category as Denial, Detection, and Deterrence, which focus on preventing, identifying, or discouraging security breaches.