service members such as a nerve agent leak in 1969. Aircraft crashes, hit-and runs and murders killed residents. The perpetrators were often unpunished, since they could not be prosecuted in Okinawa Courts. The 1970s and 80s also had severe pollution of waterways and wells with PFAS toxic chemicals in foam used by fire fighting training at US facilities such as Kadena Air Base. 1970s narcotics trade In the early 1970s, according to a US government report, Okinawa was a key conduit for smuggling drugs such as heroin from Thailand via Okinawa to the United States. It was called "The Okinawa System” in the global drug trade. A testimony by a head of the Department of Defense said that drug abuse was "quite extensive." It began in the second half of 1968; marijuana was smuggled from Thailand to Okinawa and grown near an unidentified US Marine Corps training area in northern Okinawa. A package of marijuana fell from an aircraft, and another was discovered at a military post office. From the mid-1970s onwards, LSD and heroin became more prevalent. Deserters worked as "passport civilians" and smuggled the drugs into Okinawa. A lack of customs inspections made smuggling easy. There were well organized Ryukyuan smuggling rings who brought heroin, LSD, and marijuana to Okinawa, and produced LSD on the island. 21st century In 2013, following escalating tensions following competing claims to the uninhabited Senkaku Islands, the People's Republic of China began questioning Japan's sovereignty to the island of Okinawa, citing its past as the independent tributary state of Ryukyu. On 31 October 2019, the main courtyard structures of Shurijo were destroyed in a fire. It marked the fifth time that Shurijo was destroyed following previous incidents in 1453, 1660, 1709 and 1945. On 31 October 2019, a large fire burned down sections of Shuri Castle; "Six castle buildings occupying some in total were gutted." Rebuilding efforts were underway as of 10 February 2020. Demographics As of September 2009, the Japanese government estimates the population at 1,384,762, which includes American military personnel and their families. The Okinawan language, called Uchināguchi, is spoken by adults only, but several local groups promote the use of the Okinawan language by younger people. Whereas the northern half of Okinawa Island is sparsely populated, the south-central and southern parts of the island are markedly urbanized—particularly the city of Naha and the urban corridor stretching north from there to