The STOP Illicit Drones Act prohibits the Federal Aviation Administration from providing federal funding or support to entities from six designated countries—China, Russia, Iran, North Korea, Venezuela, and Cuba—for projects involving unmanned aircraft systems, or drones. The FAA Administrator can add other countries to this list as deemed necessary. The bill affects aviation research grants, workforce development programs, centers of excellence, airport improvement projects, and other FAA funding programs related to drones. It also bars the FAA from operating, purchasing, or contracting with covered unmanned aircraft systems, with limited exceptions for testing, intelligence operations, and safety research. The FAA must replace any drones from covered countries with systems made in the United States or allied nations within one year and report to Congress within 180 days on the changes made to prevent acquiring drones from these restricted entities.