This report, published the Royal United Services Institute (RUSI), examines the efforts currently underway in Europe and the US to develop new combat aircraft over the next fifteen to twenty years. It considers the advantages of Unmanned Combat Aerial Vehicles, such as expendability, the simplicity of manufacturing and deploying one, and the combat endurance. The report ends with the suggestion that a mix of manned and unmanned aircraft would offer a pathway to a capable and maintainable air force for NATO countries.