In this episode, Lieutenant Colonel Laura West, Solf-Warren Chair and Professor in the National Security Law Department (ADN) at The Judge Advocate General's Legal Center and School (TJAGLCS), interviews department colleague, Lieutenant Colonel Dan Maurer, about an emerging issue in National Security Law (NSL). LTC Maurer discusses the recently fielded “ePPO” app, a cell phone-accessible program that permits Ukrainian civilians to visually identify, locate, and track the trajectory of airborne threats like Russian drones, helicopters, and rockets. Given a State’s duty to take feasible precautions and constant care to prevent or limit civilian collateral harms, LTC Maurer analyzes whether these conditions (a government actively providing the means or encouragement to engage in direct participation in hostilities (DPH)) trigger a legal duty on the State to warn its civilians of the legal consequences of their DPHing. The question is broader than the “ePPO” app itself, but the Ukrainian context provides a starting point for examining how modern technology pushes against the boundaries of conventional international law.