There has been a significant increase in the proliferation of military uninhabited aerial systems (UAS), as shown by an increase in total UAS and loitering munition arms transfers, which rose from 736 units in 2001-2010 to 1,734 units in 2011-2020. To better understand this development and the prominent role of UAS in recent conflicts, this report seeks to answer three key questions: (1) Which countries are driving the greater demand for UAS? (2) Where is the supply to meet the demand coming from? And (3) where does the U.S. industrial base stand in the face of such widespread and evolving proliferation of UAS? Two case studies are vital to understanding the role of UAS in modern warfare: the Nagorno-Karabakh war between Armenia and Azerbaijan, and the early stages of the Russian invasion of Ukraine. By analyzing these cases in addition to U.S. defense contracting and international UAS trends, the authors arrive at four main findings: UAS and loitering munitions provide a wide range of capabilities to a growing range of states; Ukraine has led the field in experimenting with such capabilities against a great power, but the future of UAS employment by frontline states is uncertain; there are a growing number of suppliers of such capabilities, most notably China; and the United States has increased its exports of UAS but primarily to trusted allies.