  The security of cyber-physical systems is first and foremost a safety
problem, yet it is typically handled as a traditional security problem, which
means that solutions are based on defending against threats and are often
implemented too late. This approach neglects to take into consideration the
context in which the system is intended to operate, thus system safety may be
compromised. This paper presents a systems-theoretic analysis approach that
combines stakeholder perspectives with a modified version of Systems-Theoretic
Accident Model and Process (STAMP) that allows decision-makers to strategically
enhance the safety, resilience, and security of a cyber-physical system against
potential threats. This methodology allows the capture of vital
mission-specific information in a model, which then allows analysts to identify
and mitigate vulnerabilities in the locations most critical to mission success.
We present an overview of the general approach followed by a real example using
an unmanned aerial vehicle conducting a reconnaissance mission.
