Off the south coast of China (Hainan), the Chinese navy is installing underwater communications cable links with its small land bases in the South China Sea. China currently occupies fifteen reefs and artificial (with dredged up sand) islands. This island building process began over a decade ago and by 2015 the dredging had created seven artificial reefs and small islands for China to begin construction of buildings on six. The three largest (Mischief Reef, Fiery Cross Reef and Subi Reef) eventually had roads, docks, airstrips and aircraft hangars on six of them with construction or reconstruction continuing to the present. By 2022 China claimed to have 5,000 personnel stationed on these islands and most had radars and a growing number of weapons installed. There were shelters for anti-aircraft and anti-ship missiles, as well as hangars for aircraft to protect them from the corrosive effect of salt water. This is something navies with aircraft carriers have to do for aircraft based on the carriers. Without the application of anti-corrosion coating, the aircraft soon develop equipment problems. The salty sea air is a problem for radars and other exposed electronic equipment components. The underwater communications cables will lessen dependence on equipment providing wireless communications.
By 2020 China was operating some of its Y-8FQ ASW (Anti-submarine Warfare) aircraft from a 3,100 meter (10,000 foot) airstrip on the Fiery Cross (Yongshu) Reef airbase. This base was completed in 2016 by dredging up enough sand to create a 271 hectare (677 acre) artificial island. Before that, there were two tiny “islands” that were rocky outcroppings only exposed at low tide. Those rocks were the part of the reef that was a hazard and one of the ships that sank there in the 19th century was the Fiery Cross. The reef was most frequently visited by Vietnamese fishermen because the closest land, 600 kilometers away, was Vietnam. Rarely did Chinese fishermen visit because China was over a thousand kilometers away. China made a claim to the area in the 1930s, when Vietnam was a French colony and China was at war with Japan. In the 1970s China used force (some brief naval skirmishes) to force Vietnam out of the area. The Chinese claim is not recognized by international treaties, which China has signed, specifying who owns what offshore.
Fiery Cross Reef is within the Spratly Islands. China describes the Fiery Cross facility as a naval rescue station but most of the time military aircraft are operating from the airbase. As many as 500 military personnel are stationed on Fiery Cross but the normal garrison is about half that. The base now has air-search radar and anti-aircraft weapons. There are also docks large enough to accommodate an aircraft carrier and storage areas for water and fuel. While some rainwater can be captured, most water must be shipped in. Vegetables have been grown in its sandy soil, but that requires freshwater. All supplies have to be regularly shipped in from mainland China. A special fleet of transports has been built to supply the growing number of South China Sea bases.
The Spratlys are a group of some 100 islets, atolls, and reefs that total only about five square kilometers (1,200 acres) of land, but sprawl across some 410,000 square kilometers of the South China Sea. About 45 of the islands are currently occupied by small numbers of military personnel. China claims them all but long occupied only eight while Vietnam has occupied or marked 25, the Philippines 8, Malaysia 6, and Taiwan one. In 2014 China began its sand dredging operation to turn three reefs into artificial islands. Fiery Cross is the largest of these, so far.
The Fiery Cross airbase, which occupies most of the island, has twelve reinforced concrete hangars for combat aircraft and four larger hangars for aircraft like the Y-8, which is similar to the American C-130 and used for a wide variety of special tasks, like EW (Electronic Warfare), ELINT (Electronic Intelligence Collection), AWACS (aerial warning and control), AEW (early warning) and ASW (anti-submarine warfare). Most of the 150 Y-8s (and slightly longer Y-9s) are still used as transports but over the years at least a third of the Y-8s have been converted to other uses.
By 2021 the hardest working ships in the South China Sea were two Chinese two replenishment (“sustainment”) ships designed expressly to support Chinese islands created or occupied in the South China Sea. Despite being less than ten years old, the two ships are scheduled for upgrades and eventually some major maintenance. The first of these ships entered service in 2015 and second in 2019. Named Sansha 1 and Sansha 2, they are kept busy supplying Sansha City Island and many smaller islands to the south. The two Sansha ships are actually a smaller (7,800 ton) replenishment ship designed specifically for moving up to 2,200 tons of supplies and equipment per voyage to a lot of small island bases in the South China sea. They are RO/RO (Roll On/Roll Off) type ships so it is easier to drive vehicles off onto the docks being built on many of these tiny (some man-made) islands. The Sanshas have a helicopter pad for small (four ton) helicopters like the Z-9. They will replace most of the collection of commercial ships currently used to resupply these island bases.
All Chinese activity and territorial claims got rolling in a big way after 2012, when China declared one of the Paracel islands (Woody Island) to be the center of a new Chinese municipality (city). Sansha is now one of 19 prefectures of Hainan province in southern China. Hainan is itself a large island off the Chinese coast with a population of ten million. Sansha City is the smallest prefecture in Hainan in terms of land area (13 square kilometers) and population (a few thousand). Sansha is actually Woody Island and dozens of smaller bits of land (some of them shoals that are under water all the time) in the Paracels and the Spratly Islands to the south. In fact, the new "city" lays claim to two million square kilometers of open sea (57 percent of the South China Sea). This is part of a strategy based on the ancient principle that, when it comes to real estate, "possession is 9/10ths of the law." It's the law of the jungle, because all the claimants are armed and making it clear that, at some point down the road, force will be used to enforce claims. Since 1975, there have been two naval battles, and dozens of minor clashes by the rival claimants to the Paracels. With the establishment of Sansha City, China is saying the next time it could be a war, because a government has to defend its sovereign territory.
Currently Woody Island has a permanent population of nearly two thousand people who have to be supplied, even with water, at great expense from the Chinese mainland. Most island occupants are military and police personnel, who serve on the island for two years, and civilian officials, who serve six-month tours. There is a small fishing community and facilities for fishing boats to tie up and the crews to come ashore for some rest. There are also some tourist attractions. Woody Island is about 340 kilometers from Chinese territory (Hainan Island) and thus within China's exclusive economic zone (EEZ). The expense of maintaining Sansha is a minor cost when you consider that this move makes many disputed islands, atolls, and reefs officially part of China, at least as far as China is concerned.
China will frequently contact foreign military aircraft flying over or past one of their occupied artificial islands and warn them that Chinese permission is needed for overflights. So far, the foreign aircraft have ignored these warnings and their governments quietly informed China that firing on any of these aircraft would result in return fire against its island bases. If there is any escalation, China will have to start it and face the consequences.