This course of weapons dates to at least the 1980s, when Israel designed the Harpy loitering munition for use from the suppression of enemy air defenses (SEAD). China would later on purchase the Harpy from Israel in 1994 and has long been researching loitering munitions for more than 20 years. https://travisamwhs.goabroadblog.com/37245287/drone-survey-for-environmental-monitoring-bd-things-to-know-before-you-buy