From the Document: "As of March 2020, the Federal Aviation Administration (FAA) had registered more than 1.5 million unmanned aircraft systems (UAS), often referred to as drones. More than 70% are operated by recreational users. FAA estimates that by 2024, about 2.3 million UAS, including 1.5 million recreational drones and model aircraft and about 800,000 commercial UAS, will be registered to fly in U.S. airspace. As the UAS market expands, there may be an increasing risk that rogue drones that either fail to obey safety rules or are operated for nefarious purposes could threaten manned aircraft operations, airports, critical infrastructure facilities, and high-profile events. These concerns have prompted Congress to examine options for detecting and interdicting drones."
CRS In Focus, IF11550
Congressional Research Service: https://crsreports.congress.gov/