The UAS is typically controlled by conspirators on the outside in collusion with an inmate. There have been multiple such UAS incidents reported worldwide. Examples of such incidents are cited from the United States, Canada, Mexico, Ireland, Australia, and the United Kingdom. In the United States, UAS-delivered contraband has been reported by correctional agencies in California, Maryland, Georgia, Ohio, South Carolina, and Oklahoma. The incidence of UAS-delivered contraband to the grounds of correctional institutions is expected to increase as UAS products become more accessible. Regarding prevention and mitigation of this UAS threat to the security of correctional institutions, current correctional countermeasures are either nonexistent, ineffective, or cost-prohibitive. Interceptors may not be viable; jammers are illegal; and sensors are expensive and susceptible to false alarms and delayed response time. Prior to developing UAS policies and spending money on countermeasures, a comprehensive risk assessment is required. It is likely that a layered system of low-tech policies and high-tech sensor and detection systems will provide the best overall UAS detection and response system for correctional institutions. 4 figures