The article presents the state of the art of utilizing unmanned aerial vehicles (UAVs) to monitor critical infrastructures (CI). First, the authors formulate the key CI monitoring tasks and provide examples of multi-UAV system utilization for their performance. The article further presents specifications for reliability-based multi-UAV mission planning, followed by a discussion of respective models. Then it provides a detailed example of planning the monitoring of a nuclear power plant in a post-accident period. Another example includes an analysis of cyberattacks on Internet of Drones (IoD) monitoring systems, with detailed consideration of IoD monitoring systems in view of possible cyberattacks. The potential of implementing artificial intelligence and machine learning methods in UAVs is also discussed. Finally, the authors propose adapting an advanced security assurance case to provide cybersecurity of the multi-UAV mission.