Threat-driven security is a systematic system-level approach that is driven by a clear understanding of the security need � it is not arbitrary application of security technologies based on their perceived effectiveness or hype. Using this systematic approach, the strength of a protection is easily gauged through simple identification of the weakest link in the design. This presentation will review our approach to identifying security vulnerabilities, determining viable mitigations, and developing a threat tree that leads to a robust threat-driven protection.