Unmanned aircraft systems (UASs) have played an important role in warfare over the past two decades, including to conduct counterterrorism operations. To better understand the utility of UASs, this latest report from CSIS adopts a comparative case study approach and examines the Nagorno-Karabakh war in 2020, Ukraine war in 2022, and Northern Edge-21 exercise in the Indo-Pacific in 2021. These cases demonstrate that UASs have been increasingly integrated into combined arms warfare, a major change from the past. In addition, UASs are likely to play an increasingly important role in several types of missions as part of strategic competition and warfare with such countries as China and Russia.