Brunei, Indonesia, Malaysia, the Philippines, the People's Republic of China (PRC), Taiwan (Republic of China/ROC), and Vietnam have conflicting island and maritime claims in the South China Sea. The disputes involve the islands, reefs, banks, and other features of the region, including the Spratly Islands, Paracel Islands, Scarborough Shoal, and various boundaries in the Gulf of Tonkin. The waters near the Indonesian Natuna Islands, which some regard as geographically part of the South China Sea, are disputed as well.
An estimated US$3.36 trillion worth of global trade passes through the South China Sea annually, which accounts for a third of the global maritime trade. 80 percent of China's energy imports and 40 percent of China's total trade passes through the South China Sea. Claimant states are interested in retaining or acquiring the rights to fishing stocks, the exploration and potential exploitation of crude oil and natural gas in the seabed of various parts of the South China Sea, and the strategic control of important shipping lanes. Maritime security is also an issue, as the ongoing disputes present challenges for shipping.
According to researchers, claims to any of the features were not seriously made until the 19th or the early 20th century. The Paracel Islands, currently occupied by China, are contested by Taiwan and Vietnam. The Spratly Islands are claimed by all three, where Vietnam occupies the greatest number of features and Taiwan occupies the largest, Taiping Island. Brunei, Malaysia, and the Philippines also claim some of the features in the island chain. By the 1970s, the Philippines, Taiwan, and Vietnam had militarily occupied one or more of the Spratly Islands. By 2015, the PRC had established 8 outposts, Malaysia 5, the Philippines 8, Taiwan 1, and Vietnam 48.
For decades, the Philippines and Vietnam were the most active in building artificial islands in the area, but from 2014 to 2016 China's construction activity outpaced them. By 2023, China had reclaimed around five square miles with its artificial islands, at least one of which housed military equipment.
China's actions in the South China Sea have been criticized as part of its "salami slicing"/"cabbage wrapping" strategies. Since 2015, the United States and other states such as France and the United Kingdom have conducted freedom of navigation operations (FONOP) in the region. A 2016 arbitration tribunal, without determining the sovereignty of any of the islands, concluded that China lacks historical titles to the maritime areas within the nine-dash line. The ruling was rejected by both the PRC and ROC.
Disputes in the South China Sea region.
The disputes involve both maritime boundaries and islands. There are several disputes, each of which involves a different collection of countries:
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Location of the major islands in Spratly Islands. The eastern Dangerous Ground area contains many other reefs. 
History.
In 1734, the Spanish colonial government in the Philippines published the first edition of the Velarde map. In 1792, the Spanish colonial government of the Philippines named Scarborough Shoal "Basinloc" during a survey. The 1808 "Carita General del Archipelago Filipino" and the 1875 "Carita General del Archipelago Filipino" republished depictions from the Velarde map.
According to retired Philippine Supreme Court justice Antonio Carpio, territories in these maps fell under the sovereignty of Spanish Philippines, including Scarborough Shoal (called "Panacot" in the indigenous language in the maps) and the Spratly Islands ("Los Bajos de Paragua" in the maps).
China has a different perspective, asserting that maps produced in 1775, 1810 and 1817 include the Spratly and Paracel islands as Chinese territory. Vietnam's first maps extending its territory to the Spratly Islands were published in 1830 under Emperor Minh Mang.
After the Spanish-American War, Spain lost and ceded the territory of the Philippines to the United States through the 1898 Treaty of Paris. The 1898 Treaty of Paris created a treaty line, where Scarborough Shoal, the Spratly Islands, and parts of Tawi-tawi continued to be under Spanish sovereignty. This led to talks between Spain and the United States, which ended upon the signing of the 1900 Treaty of Washington, which rectified retroactively the 1898 Treaty of Paris. As of 2023, the United States takes no position on sovereignty over the geographic features of the South China Sea.
In 1909, the Chinese reacted to Japanese interest in exploiting guano in the Paracel Islands by mapping them, stationing Chinese navy personnel, and hoisting a flag to reassert Chinese sovereignty.
In 1930, the United States and the United Kingdom signed a treaty, where the United Kingdom recognized the territory of Philippines as it related to the boundaries of the Philippines and North Borneo which included Scarborough Shoal and islands in the Spratlys. This treaty is internationally binding, however in 1961 the United States sent a diplomatic note to the Philippines pointing out that neither country that signed agreed with the subsequent Philippines interpretation of this treaty as applying to a claim for the waters within the Treaty Limits as part of Philippine territory. Carpio claims that this effectively binds the United Kingdom's successor countries, such as Malaysia and Brunei, to recognize Philippine ownership of the islands.
In 1932, France occupied the Paracels and laid claims on the territory. China protested and filed a Note Verbale stating the Paracels were the "southernmost part of Chinese territory". According to Carpio, this can be interpreted as negating China's later claim towards the Spratlys. He also said that when France formally claimed six features in the Spratly Islands in July 1933, it did so for itself, not as a representative of French Indochina and its successors such as Vietnam, although another source disagrees with that assertion. Accounts also differ as to whether China (and Japan) protested the 1933 French claim or not.
By May 1939, the Japanese occupied much of Southeast Asia, including the Paracel and Spratly Islands. During World War II, the Empire of Japan used the islands in the South China Sea for various military purposes and asserted that the islands were not claimed by anyone when the Imperial Japanese Navy took control of them. Manila claims that their actual sovereignty was under the American territory of the Philippines at that time.
During the Second Sino-Japanese War, "China Handbook (1937–1943)" stated that its southernmost territory is Triton Island of the Paracels. In the 1944 revised edition, the handbook said China, Indochina, and the Philippines all claimed the Spratlys. According to retired Philippine judge Antonio Carpio, China held this position when it published another edition in 1947 and China's claim is "defective" under international law.
In 1947 the Republic of China (ROC) published an "eleven-dash line" in the South China Sea. Chinese names for the island groups, which were regarded as under Chinese administrative jurisdiction, were announced in December 1947 by the ROC Ministry of the Interior. In 1949, the People's Republic of China (PRC), which defeated the ROC in the Chinese Civil War, announced that it had inherited this claim. The PRC later revised the claim by removing two of its dashes in the Gulf of Tonkin amidst warming ties with Ho Chi Minh's North Vietnam. The ROC government on Taiwan has continued to use eleven dashes to this day.
In August 1951, Zhou Enlai, then the PRC's foreign minister, claimed that the Paracel and Spratly Islands "have always been Chinese territory". During the 1951 San Francisco peace conference, the Soviet Union made a motion to grant the Paracels and the Spratlys to China, but it was defeated by vote. Japan relinquished control of the islands in the South China Sea with the signing of the Treaty of San Francisco on 9 September 1951 but did not specify the new status of the islands. Tran Van Huu as Vietnamese representative stated that “in order to annul the seeds of possible disputes, we claim our sovereignty over Hoang Sa and Truong Sa archipelagos”, referring to the Paracels and the Spratlys. Overall, the communist bloc favored PRC claims. Australia was opposed to the bloc's influence. The United States was torn between French "colonialist" claims and Chinese (ROC) claims which might end up helping the PRC. Britain favored ambiguity due to its previous claims on some of the islands.
The Geneva Accords of 1954, which ended the First Indochina War, gave South Vietnam control of the Vietnamese territories south of the 17th Parallel. The South Vietnamese government claimed the Paracels and the Spratly. In 1955, France clarified through international notes that the Spratlys belonged to "the French Union" because they were not attached to Vietnam when Cochinchina was ceded and North Vietnam did not protest Chinese claims.
North Vietnam received aid from China during the Vietnam War and recognised Chinese claims on the Paracels and Spratlys. After winning the war against the United States, North Vietnam retracted its recognition. During June 1977 discussions with PRC president Li Xiannan amid rising tensions between the two countries, Pham stated that the 1958 recognition of China's sovereignty over the Paracels was only made under the pressure of America's war against Vietnam.98
In the 1970s, the discovery of the potential for petroleum resources in the South China Sea prompted an increase in occupation activity by claimants.254 From 1971 to 1973, the Philippines began occupying five features and South Vietnam began occupying six.254 Concerned that its claims would be weakened by the activity of other claimants, China increased its physical presence in the area.254 It conducted surveys around the Paracels and the People's Liberation Army Navy built a harbor and wharf on Wood Island (in the Paracels) in 1971.254
In 1974, when a North Vietnamese victory in the Vietnam War began to seem probable, the PRC used military force in the Paracel Islands and took Yagong Island and the Crescent group of reefs from South Vietnam. The "Operation Tran Hung Dao 48" was a campaign conducted by the South Vietnamese Navy in February 1974 to station troops on unoccupied islands to assert Vietnam's sovereignty over the Spratly archipelago after the Battle of the Paracel Islands. The government of the PRC wanted to prevent the Paracel islands from falling under the control of North Vietnam, which at the time was an ally of the Soviet Union. After not resisting during the initial Vietnamese attack, the PRC launched what they regarded as a "counterattack in self-defense". The United States, in the middle of détente with the PRC, gave a non-involvement promise to the PRC, which enabled the People's Liberation Army Navy to take control of the South Vietnamese islands.
In the later half of 1970s, the Philippines and Malaysia began referring to the Spratly Islands as being included in their own territory. On 11 June 1978, the Philippines through Presidential Decree No. 1596, declared the north-western part of the Spratly Islands (referred to therein as the Kalayaan Island Group) as Philippine territory.
In 1988, the PRC and Vietnam fought each other near the Johnson Reef. The PRC had obtained a permit from the Intergovernmental Oceanographic Commission to build five observation posts for the conduction of ocean surveys, and one of the permitted observation posts was allowed to be located in the Spratly islands region. The PRC chose to build its observation post