Unmanned aerial systems (UAS) offer new or improved military capability in many airpower applications. Contemporary UASs range in size from aircraft with wingspans exceeding 150 feet to vehicles that fit into the palm of an operator’s hand. Medium-sized unmanned aircraft such as the MQ-1B Predator have become icons of American counterterrorism warfare, but small unmanned aerial systems (SUAS) have performed significant roles in militaries around the globe as well. SUASs provide game-changing potential for small militaries and nonstate actors by enabling airpower capability that may have been previously out of reach. More advanced militaries can also leverage SUAS capability to enhance existing combat systems.