Book excerpt: Unmanned Aircraft Systems (UAS) are an integral part of the US national critical infrastructure. They must be protected from hostile intent or use to the same level as any other military or commercial asset involved in US national security. However, from the Spratly Islands to Djibouti to heartland America, the expanding Chinese Unmanned Aircraft Systems (UAS / Drone) industry has outpaced the US technologically and numerically on all fronts: military, commercial, and recreational. Both countries found that there were large information security gaps in unmanned systems that could be exploited on the international cyber-security stage. Many of those gaps remain today and are direct threats to US advanced Air Assets if not mitigated upfront by UAS designers and manufacturers. The authors contend that US military / commercial developers of UAS hardware and software must perform cyber risk assessments and mitigations prior to delivery of UAS systems to stay internationally competitive and secure. The authors have endeavored to bring a breadth and quality of information to the reader that is unparalleled in the unclassified sphere. This book will fully immerse and engage the reader in the cyber-security considerations of this rapidly emerging technology that we know as unmanned aircraft systems (UAS). Topics covered include National Airspace (NAS) policy issues, information security, UAS vulnerabilities in key systems (Sense and Avoid / SCADA), collision avoidance systems, stealth design, intelligence, surveillance and reconnaissance (ISR) platforms; weapons systems security; electronic warfare considerations; data-links, jamming operational vulnerabilities and still-emerging political scenarios that affect US military / commercial decisions.