With an increased reliance on Unmanned Aerial Systems (UAS) as mission assets and the dependency of UAS on cyber resources, cyber security of UAS must be improved by adopting sound security principles and relevant technologies from the computing community. On the other hand, the traditional avionics community, being aware of the importance of cyber security, is looking at new architecture and designs that can accommodate both the safety oriented principles as well as the cyber security principles and techniques. The Air Force Research Laboratories (AFRL) Information Directorate has created the Agile Resilient Embedded System (ARES) program to investigate mitigations that offer a method to "design-in" cyber protections while maintaining mission assurance. ARES specifically seeks to 'build security in' for unmanned aerial vehicles incorporating security and hardening best practices, while inserting resilience as a system attribute to maintain a level of system operation despite successful exploitation of residual vulnerabilities.