American Security Drone Act of 2020 This bill bans the procurement, operation or use by the federal government of unmanned aircraft systems (UAS) that are manufactured or assembled by certain foreign entities, including entities subject to influence or control by China, with exceptions for certain research, training, or testing activities. Government-issued purchase cards may not be used to procure any UAS from a foreign entity. All executive agencies must account for existing inventories of UAS manufactured or assembled by a foreign entity in their personal property accounting systems, with exceptions. The Government Accountability Office must report on the amount of commercial off-the-shelf drones and UAS procured from foreign entities. The Office of Management and Budget shall (1) establish a government-wide policy for the procurement of UAS, taking into account information security; and (2) contract with a federally-funded research and development center to study certain UAS-related issues.