To meet the challenging technical requirements of DHS SBIR topic DHS201-008, Cobalt Solutions is proposing 5G-PRT: 5G Passive RADAR-based UAS Tracking and Targeting. 5G mmWave base-stations are being densely deployed in the urban core of US cities to support the demands of telecommunications and 5G-unique applications (e.g. self-driving cars, low latency robotic control, ubiquitous augmented reality, and high demand video streaming/sharing.) Meanwhile, the coming proliferation of UAS activity in this same urban core will be a commercial boon but also a public safety and National security threat, if bad actors employ drones to create mischief or foster attacks. The research we propose will use these same (free) 5G mmWave signals deployed in the urban core as the "illuminating" signal in our 5G- PRT system for tracking and targeting UAS in the urban canyon environment. Our partner, Miles Space has already demonstrated inNvative passive UAS tracking using 3G/4G, in more benign environments, for SOCOM. Miles Space employs machine learning algorithms to optimize processing speed in order to support targeting timelines.Our Cobalt PI, Dr. Robert Daniels, is a recognized expert in 5G and RADAR. While the concept is Nt without technical risk; he is confident that 5G is well suited for UAS tracking in the Urban Canyon environment. He previously co-founded Phazr Inc., the only US-based vendor to produce certified mmWave 5G base-stations. Cobalt's 5G expertise and vision, together with Miles Space proven passive drone tracking techNlogy, will create the potential for huge inNvation and commercialization impact for DHS.