Since 2019 Vietnam has been visibly improving its military facilities on several of the Spratly islands that China has been claiming even though the islands are closer to Vietnam and were often occupied by Vietnamese civilian or military facilities. The latest Vietnamese improvements are most obvious (via commercial satellite photos) on West Reef and Sin Cowe Island. The most obvious change in West Reef is that it is now larger (28 hectares/70 acres) and most of it is recently dredged up sand. Sim Cowe also had about 11 hectares of land added via dredged up sand. Most of that new land is now covered with military structures, including bunkers for coast defense guns or missiles, radars and ELINT (Electronic Intelligence) sensors plus landing pads (for helicopters) or short airstrips. Although Russia is an ally of China, that has not halted the sale of Russian submarines and other weapons to Vietnam. The United States recently proposed installing about $5 billion worth of missiles and sensors on islands within or near the South China Sea that are threatened by China.
To those unfamiliar with the South China Sea situation, the American proposal seemed to be a major escalation, but it isn’t. All the nations threatened by Chinese claims are improving the defenses on the islands they occupy. In addition, nearly once a month the U.S. sends warships through waters China claims in the South China Sea, and this is often done within sight of Chinese occupied islands. Many of these “islands” were recently created or expanded with dredged up sand.
China has always considered Vietnam the most aggressive opponent of Chinese claims, and the two countries have fought near disputed islands several times since the 1980s. Vietnam has not backed down but has been forced to back away several times and is preparing to make any future Chinese aggression very difficult, if not impossible without a major military operation. Vietnam knows that China wants to avoid being such an obvious aggressor in these matters because most nations, as well as international law (and the tribunals that hear appeals) oppose the Chinese claims.
China can be persuaded to back off. Vietnam was often the cause of failed Chinese aggression and embarrassed China. For this reason, China and Vietnam agreed to establish a hotline in 2013, after two years of negotiations, to ensure that any future disputes did not turn violent unintentionally. This was a good idea and the hotline was first proposed by China because Vietnam and China have been fighting each other for centuries. In the past the violence was mainly over disagreements about Vietnam’s status. China considered Vietnam a rebellious province, while Vietnam considered itself independent.
In the late 19th century French forces were invited in to support one faction in another round of Vietnamese internal strife. The French soon took over all of what is now Vietnam and united all of Vietnam for the first time. Despite extensive Chinese help in fighting the French after World War II and support for North Vietnam efforts to invade South Vietnam, China and a reunited Vietnam fought a short war in 1979. Technically China won, but in reality the Chinese got clobbered and have never got over that. In 1988 China and Vietnam fought a naval battle off the Spratly islands. This was a Chinese victory, in which a Chinese warship sank a Vietnamese transport carrying troops headed for one of the disputed islands. This was followed by Chinese troops establishing garrisons on some of the islands. In 1992, Chinese marines landed on Da Lac reef, in the Spratly Islands. In 1995, Chinese marines occupied Mischief Reef, which was claimed by the Philippines, but as a pointed reminder to Vietnam as well. China has since expanded its naval infantry force and built several large amphibious warships to land naval infantry on a defended island. With this history of violence, and continued disputes over some islands, a hot-line was a good idea but Vietnam still fears Chinese aggression and is preparing for more fighting.
This growing animosity is not restricted to Vietnam. China continues to threaten nations that get too close to the Chinese coast, or challenge Chinese territorial claims. The only problem is that China has a definition of territorial waters that the international community does not recognize. International law (the 1994 Law of the Sea treaty) recognizes the waters 22 kilometers from land as under the jurisdiction of the nation controlling the nearest land. That means ships cannot enter these "territorial waters" without permission. Moreover, the waters 360 kilometers from land are considered the Exclusive Economic Zone (EEZ), of the nation controlling the nearest land. The EEZ owner can control who fishes there, and extracts natural resources (mostly oil and gas) from the ocean floor. But the EEZ owner cannot prohibit free passage, or the laying of pipelines and communications cables. China, however, claims that foreign military ships and aircraft cannot enter its EEZ, and sometimes uses force to block entry. This is usually done with Chinese owned fishing or cargo ships, which move very close and persuade the “invaders” to leave. It is feared that eventually China will use one of its growing number of warships to challenge some foreign warship "invading" its EEZ. The 1994 treaty says nothing about blocking warships from your EEZ, but some nations believe it is allowed. China is simply doing what China has been doing for centuries, trying to impose its will on neighbors, or anyone venturing into what China considers areas under its control.
For the last three centuries, China claims it has been prevented from exercising its "traditional rights" in nearby waters because of the superior power of foreign navies. First it was the cannon armed 16th century European sailing ships, then, in the 19th century, newly built steel warships from Japan. However, since the communists took over China 70 years ago, there have been increasingly violent attempts to reassert Chinese control over areas that have, for centuries, been considered part of the "Middle Kingdom" (or "zhong-guo", as in the "center of the world").
China's other neighbors are also responding to this aggressive attitude. Taiwan has reinforced garrisons on disputed islands in the South China Sea. Taiwan is particularly concerned about the Pratas Islands, which only China and Taiwan dispute control of. These are 340 kilometers southeast of Hong Kong, and 850 kilometers southwest of Taiwan. Only one of the three islands is above water, and it (Pratas Island) is 2.8 kilometers long and 850 meters wide. There were never any permanent inhabitants. Taiwan not only maintains a military garrison and an air strip there, but is adding anti-aircraft and anti-ship missiles as well. There is also "service station" for fisherman and researchers working on the island or nearby. Taiwan is upgrading the defenses of several of the disputed islands it still occupies,
More valuable and more newsworthy, though, are a larger group of islands south of the Pratas. These are the Spratlys, a group of some 100 islets, atolls, and reefs that total only about 5 square kilometers of land, but sprawl across some 410,000 square kilometers of the South China Sea. Set amid some of the world's most productive fishing grounds, the islands are believed to have enormous oil and gas reserves. Several nations have overlapping claims on the group. About 45 of the islands are currently occupied by small numbers of military personnel. China claims them all, but occupies only 8, Vietnam has occupied or marked 25, the Philippines 8, Malaysia 6, and Taiwan one.
In 2009 Taiwan built a 1,150 meter long, and 30-meter-wide air strip on Itu Aba, one of the Spratly Islands, 500 kilometers to the south. Called Taiping Island by the Taiwanese, Ita Aba is one of the largest of Spratly Islands, at about 120 acres (489,600 square meters). It has been in Taiwanese hands since the mid-1950s and has largely been used as a way station for fishermen. The island is also claimed by the Vietnamese, who call it Thai Binh. Taiwan has long maintained a small military presence on the island, and an air strip is meant to cement that control. Taiwan has since upgraded its military facilities on Ita Aba. Protests were made by Vietnam, which controls the largest group of islands, and the Philippines, which also claimed Itu Aba Island. Vietnam refurbished an old South Vietnamese airstrip on Big Spratly Island. For over a decade both the China and Vietnam have been building more structures, including armed bunkers, on the Spratly islands they occupy. Malaysia has built an air strip on its Spratly island, which it uses to fly in tourists looking for prime scuba diving. There are now believed to be seven airports in the Spratlys; three for China and one each for Taiwan, Malaysia, Philippines and Vietnam. There are several other islands with air strips or plans to build one.
China has used force, or the threat of force, to prevent Vietnam from carrying out exploration for oil and natural gas in offshore waters where international law recognizes Vietnamese exploration rights. As recently as 2020, Chinese threats forced a British firm to back off on a billion-dollar oil exploration contract it had with Vietnam,
China is also demanding that the Philippines halt oil exploration in the Spratly Islands, without saying exactly what would happen otherwise. The Philippines has asked the United States to help establish Filipino claims in the Spratly islands. China claims to own any oil and gas throughout the South China Sea. This claim is not recognized by any international agreement. China is apparently trying to bully other claimants, especially the Philippines and Vietnam, into staying away from these potential assets. All China offers are vague promises of "sharing" these undersea bonanzas. But the implication is that China will get most of the profits, with the other claimants getting little. China insists that the U.S. should stay out of this dispute as it is not one of the claimants. The quarrel has sparked nationalist passions in all the nations involved. The United States has said it will stand by many of the non-Chinese claims, and now the Americans are proposing extensive military cooperation with the nations threatened by Chinese offshore claims.
The small countries all fear that China will eventually make good on its long-standing claim to all the Spratlys, as well as all similar islands and reefs in the South China Sea. At that point, the international community will have to worry about continued free passage through an area that currently sees about two trillion dollars’ worth of cargo moved through each year. With this in mind, the United States is backing China's neighbors, and refusing to bend to Chinese demands.