China’s Maritime Disputes

After claiming exclusive rights over several South China Sea archipelagos, Japan occupies the Pratas Islands. The Japanese Imperial Navy lands on the Spratlys in December 1938 and invades Hainan Island the following February. Japan’s moves follow the Marco Polo Bridge Incident of July 1937—a battle between the Republic of China’s National Revolutionary Army and the Japanese Imperial Army—which marks the Japanese invasion of China. Japan’s military foray into the South China Sea [PDF] takes place during a decade in which France’s Indochina forces have also been present in the area, surveying the islands in the early 1930s and occupying the Paracel Islands in 1938.

After Tokyo’s surrender at the end of World War II, the United States assumes control of Japan. This includes the Ryukyu Islands, which Washington later interprets to include the Senkaku/Diaoyu Islands. The greater Ryukyu Islands are seen as being of strategic significance at a time when communism is spreading in the region. The Kuomintang-led government of China makes repeated claims to the islands and in April 1948 calls for their return. The U.S. occupation of Japan’s main islands lasts until the end of the Korean War in 1952, but the United States continues to occupy Okinawa until 1972.

The United States and forty-seven other nations sign the Treaty of Peace [PDF] with Japan in San Francisco, officially ending World War II. Japan renounces all claims to Korea, Formosa (Taiwan), the Pescadores, and the Spratly Islands in the South China Sea. The Senkaku/Diaoyu Islands are not explicitly mentioned in the treaty, though there is a tacit understanding that Japan will administer them as a part of Okinawa Prefecture. Japan is granted “residual sovereignty”—meaning full sovereignty would eventually be transferred to Japan—over the Ryukyu Islands; in turn, the United States is permitted to open military bases on Okinawa. Whether the Senkaku/Diaoyu Islands were considered part of Okinawa or ceded to Taiwan after the treaty remains a contentious issue in the present-day debate over sovereignty in the East China Sea.

The United States and Japan sign the bilateral Treaty of Mutual Cooperation and Security, a ten-year, renewable agreement stipulating that any attack on territories under Japan’s administration would require action by both countries to “meet the common danger.” (In an analogous situation, the United States is bound by a 1951 mutual defense treaty with the Philippines.) Washington has consistently asserted that the treaty covers the Senkaku/Diaoyu Islands, though it has refrained from explicitly endorsing Japan’s sovereignty claim over the islands. Some analysts believe the U.S.-Japan treaty presents the biggest deterrent to a takeover of the islands by force.

After extensive geological surveys in 1968 and 1969, a report published by the UN Economic Commission for Asia and the Far East finds “substantial energy deposits” in the seabed between Taiwan and Japan—the waters off the Senkaku/Diaoyu Islands. The paper marks one of the first credible findings of hydrocarbon resources there, reigniting interest in the region. Although China has not previously disputed Japanese claims to the islands, it asserts its own sovereignty over them in May 1970, after Japan, South Korea, and Taiwan hold talks on joint energy exploration in the East China Sea.

China and Japan formally reestablish diplomatic relations after gradually rebuilding economic ties. In China, the failure of Mao’s Great Leap Forward (1958–1962) preceding the Cultural Revolution resulted in mass starvation that forced Beijing to reevaluate its domestic policies and look to Japan for aid. The Sino-Japanese reconciliation dovetails the rapprochement between the United States and China—a change in official political allegiance from Taipei to Beijing that is a crucial factor in the establishment of diplomatic ties between Japan and China. Nixon, whose administration has made normalizing relations with the PRC a diplomatic priority, visits Beijing the same year, establishing de facto relations with the country after U.S. Secretary of State Henry Kissinger’s visit in July 1971. Trade between Japan and China surges in the period after normalization, deescalating the first round of the Senkaku/Diaoyu Islands disputes.

A year after the Paris Peace Accords, which end U.S. involvement in the Vietnam War, Chinese forces occupy [PDF] the western portion of the Paracel Islands, planting flags on several islands and seizing a South Vietnamese garrison. Vietnamese troops flee south and establish the first permanent Vietnamese occupation of the Spratly Islands. Meanwhile, Beijing builds a military installation, including an airfield and artificial harbor, on Woody Island, the largest of the Paracels. After the fall of Saigon and the reunification of Vietnam, the newly formed Socialist Republic of Vietnam upholds the South’s former claims to the Spratlys and Paracels. To this day, China maintains around one thousand troops in the Paracels.

After an extensive exploration program, the Philippines finds the Nido oil field off the coast of Palawan Island, marking the first oil discovery in the Northwest Palawan Basin. The discovery comes four years after the government passes the Oil Exploration and Development Act of 1972, which provides the legal basis for exploring and developing petroleum resources as Manila pushes for energy independence. Philippine Cities Service, Inc., the country’s first oil company, begins drilling a well in the Nido oil field and launches commercial production in 1979, yielding 8.8 million barrels that year. In 2012, the IMF notes [PDF] that the Philippines’ petroleum industry may have “significant potential” in the South China Sea, which is adjacent to the Northwest Palawan Basin.

China wages a short but bloody war with Vietnam, launching an offensive in response to Vietnam’s invasion and occupation of Cambodia in 1978, which ended the reign of the communist, Chinese-backed Khmer Rouge. The conflict marks the apex of tensions between Beijing and Hanoi, which were already running high after Vietnam established ties with the Soviet Union, China’s Cold War rival, the previous November. China had aided Vietnam in its wars against both France and the United States. Although both sides claim victory, China withdraws from Vietnam after less than a month, having failed to coerce Vietnam to leave Cambodia. Roughly thirty thousand are killed in the short-lived conflict, which marks the beginning of many border disputes between Beijing and Hanoi and bolsters Vietnam’s lingering distrust of China.

After roughly a decade of relative calm in the South China Sea, China and Vietnam clash on the Johnson Reef, marking China’s first armed conflict over the Spratly archipelago. The Chinese navy sinks three Vietnamese vessels, killing seventy-four sailors in one of the most serious military confrontations in the South China Sea. The incident occurs after Beijing, pursuing a more assertive stance in the area, establishes a physical presence on Fiery Cross Reef in the Spratlys in January 1987. In response, Vietnam occupies several reefs to monitor China’s moves. The incident unfolds amid Deng Xiaoping’s economic reforms of the 1980s, when Chinese economic activity begins shifting to the coastal provinces, and maritime resources become increasingly prized as hydrocarbons are needed to sustain growth.

Three Chinese naval vessels fight a ninety-minute battle with a Philippine navy gunboat near Capones Island in the Mischief Reef, part of the Spratly chain of islands claimed by Manila. The incident marks the first time China engages in military confrontation with an ASEAN member other than Vietnam. The clash, which triggers a crisis in Sino-Philippine relations, revives U.S.-Philippine military ties; soon after the incident, U.S. Navy SEALs conduct a joint exercise with their Philippine counterparts on Palawan Island, although Philippine President Fidel Ramos denies that this is connected to Manila’s row with Beijing. Tensions over the occupation subside by midyear, when the Philippines and China sign a nonbinding code of conduct that calls for a peaceful resolution to the territorial dispute and the promotion of confidence-building measures.

China and the United States sign the Military Maritime Consultative Agreement [PDF], the first bilateral military agreement between the two countries, which serves as a confidence-building measure after a period of frozen relations following the 1989 Tiananmen Square protests. From the mid-to-late 1990s, the Clinton administration works toward security engagement with Beijing as China’s People’s Liberation Army Navy (PLAN) begins to shift from being a mostly coastal defense force to operating a blue-water fleet beyond Chinese territorial waters. The accord aims to promote defense dialogue between naval forces to prevent misunderstandings. However, its efficacy is questioned in April 2001, when a Chinese F-8 interceptor and a U.S. Navy surveillance aircraft collide over the South China Sea, killing a Chinese pilot.

China and the ten ASEAN states reach an agreement in Phnom Penh on the ASEAN-China Declaration on the Conduct of Parties in the South China Sea [PDF], a code of conduct that seeks to ease tensions and creates guidelines for conflict resolution. The agreement comes after six years of negotiations. Beijing had previously insisted on bilateral negotiations with claimants; China’s signing marks the first time it accepts a multilateral approach to the issue. Though the declaration falls short of a binding code of conduct, as the Philippines had sought, it signals China’s recognition that such an agreement could work in its favor by limiting the risk of conflict in the area, which could involve the United States in the dispute.

After years of dispute over gas fields in the East China Sea, Japan and China sign a Joint Energy Development Agreement that includes the potentially gas-rich Chunxiao/Shirakaba field. The two countries agree to explore four fields jointly, halt development in contested waters, and collaborate on joint surveys and investment. While the accord is hailed as a major step toward maritime cooperation on energy resources—a strategic priority for both countries—China soon begins to develop the Tianwaitian/Kashi field unilaterally in 2009, stirring protest from Japan. A year later, Japan threatens to bring China to the International Tribunal for the Law of the Sea if China begins producing from the Chunxiao/Shirakaba field. Despite the milestone agreement, little has been done since then to increase joint resource development.

Malaysia and Vietnam file a joint submission to the UN Commission on the Limits of the Continental Shelf to extend their continental shelves beyond the standard two hundred nautical miles from their coastlines, renewing friction over maritime sovereignty in the South China Sea. China views this as a challenge [PDF] to its territorial claims and objects to the submission, saying it “has seriously infringed” on China’s “indisputable sovereignty” over the islands in the South China Sea. Vietnam’s claims are viewed as part of a campaign to bring the South China Sea issue to an international forum, beginning with a conference held in November 2009 in Hanoi.

The Philippines summons a Chinese envoy to express its mounting concern about naval incursions in its claimed territory after recording at least five incursions by Chinese ships in the past year near the Spratly Islands and the Amy Douglas Bank, off the coast of Palawan Island. These incursions begin in early March, when Chinese surveillance ships force a Philippine vessel conducting surveys in the Reed Bank to leave the area. Both parties declare the incident as violations of the 2002 ASEAN-China Declaration on the Conduct of Parties in the South China Sea, and the event sets off a series of skirmishes in the region between the two countries. The diplomatic standoff in June comes days after Vietnam protests China’s alleged harassment of its oil exploration ships; Vietnam had been working with multinational corporations, including ExxonMobil and Chevron, to develop hydrocarbon assets.

2012 heralds a landmark year for leadership transition in Northeast Asia, raising questions about how territorial disputes will factor into each administration’s agenda. Following a hearty election win, Abe Shinzo takes office as Japan’s prime minister for the second time on December 26. Shortly thereafter he publishes an op-ed in which he warns of the South China Sea transforming into “Lake Beijing,” and proposes a “democratic security diamond” comprising Japan, the United States, India, and Australia that would “safeguard the maritime commons stretching from the Indian Ocean region to the Western Pacific.” China also undergoes its high-profile, once-a-decade leadership transition in November, electing Xi Jinping and Li Keqiang as president and premier, respectively. Its military strategy continues to shift from land-based power to a maritime one, which its new leaders reinforce through an expansion and consolidation of marine agencies as well as rhetoric that refers to maritime rights as part of the country’s “core interests.” South Korea elects Park Geun-hye as its first female president in February 2013 amid heightened tensions over nuclear tests by the North.

Newly elected Prime Minister Shinzo Abe’s cabinet increases the country’s defense budget for the first time in eleven years, approving a $51.7 billion defense package for 2013, marking a 0.8 percent uptick. The spending increase, in addition to a 1.9 percent hike in the Coast Guard budget, comes as Abe’s administration bolsters Japan’s maritime capabilities and ability to monitor and protect the disputed Senkaku/Diaoyu Islands in the East China Sea. In January, Abe visits Vietnam, Thailand, and Indonesia in a push to boost ties with ASEAN countries.

U.S. President Barack Obama, on the last leg of a four-nation Asia tour, signs a new ten-year military pact with the Philippines. Under the Enhanced Defence Cooperation Agreement, the U.S. military would gain increased rotational troop presence in the country, engage in more joint training, and have greater access to bases across the archipelago, including ports and airfields. The deal is the centerpiece of Obama’s first visit to the Philippines, the United States’ oldest ally in the region, and underscores the administration’s commitment to the Asia “pivot.” While Obama expresses solidarity with Manila as it seeks international arbitration over the disputed South China Sea islands, he insists that the deal is not aimed at containing China.

A U.S. Navy patrol sails within twelve nautical miles of Chinese-built islands to assert “freedom of navigation” in disputed waters in the South China Sea. China’s ambassador to the United States calls the patrol a “serious provocation, politically and militarily.” The mission comes after an August 2015 U.S. Department of Defense report says China has reclaimed nearly three thousand acres on islands known as the Spratlys. China’s land reclamation efforts, including infrastructure development, dwarf the one hundred acres built up by other claimants over the last forty-five years. At the annual 2015 Shangri-La Dialogue in Singapore, U.S. Secretary of Defense Ash Carter urges Beijing to cease its building projects, expressing concern over the prospect of further militarization in the South China Sea.

Beijing deploys surface-to-air missiles on Woody Island, a land mass in the Paracel Island chain in the South China Sea, according to U.S. and Taiwanese officials. U.S. and regional officials warn that the deployment may signal a “militarization” of the maritime disputes, while China argues that the installation of missiles falls within its rights for defense on what it considers sovereign territory. Some experts suggest that the move may be a response to U.S. freedom of navigation operations in disputed waters. The People’s Liberation Army air force also stationed J-11 fighter aircraft in the Paracels in October 2015, according to Chinese media reports.

A Panamanian-flagged, Iranian-owned tanker carrying nearly one million barrels of natural-gas condensate collides with the CF Crystal, a Hong Kong–flagged cargo ship carrying grain from the United States in the East China Sea, 160 nautical miles off the coast of Shanghai. The tanker, traveling from Iran to South Korea, catches fire, explodes, and sinks after eight days ablaze, killing all thirty-two crew members and causing a major oil spill of both condensate—ultra-light fuel oil—and fuel. Experts say it is the largest-ever spill of condensate and the slick risks contaminating some of the world’s most abundant fisheries. Seven vessels (five Chinese, one Japanese, and one South Korean) are involved in clean up efforts in the Northeast Asian waters. China, Hong Kong, Iran, and Panama agree to jointly investigate the collision.

Philippine President Rodrigo Duterte warns he will send troops on a “suicide mission” if China continues to send ships near the Philippines-occupied Thitu Island in the Spratly chain. His threat comes after more than two hundred Chinese ships were seen near the island from January to March. The Philippines had been constructing a beaching ramp on the island, which is also claimed by China, to ease the delivery of construction equipment and supplies.

China more aggressively asserts its claims in the South China Sea as countries in the region battle the coronavirus pandemic. In February, a Chinese naval ship reportedly aims its weapons control system at a Philippine naval ship in the Spratly Islands. The next month, China opens new research stations, which include defense silos and military-grade runways, on the Fiery Cross and Subi Reefs. In April, Vietnam lodges a formal complaint over China’s actions after a Chinese vessel rams and sinks a Vietnamese fishing boat near the Paracels. Soon after, Beijing establishes two administrative districts that cover the Paracel and Spratly Islands; the Philippines and Vietnam denounce the move.

China steps up its intimidation tactics in the wake of President Duterte’s hardening support for the 2016 Hague ruling that rejected the nine-dash line, a legal decision also endorsed by France, Germany, and the United Kingdom. In March 2021, China deploys two hundred ships to Whitsun Reef, part of the Philippines’ exclusive economic zone (EEZ). While Beijing claims that the ships are a “fishing fleet,” Manila says they appear to be operated by military personnel. In November 2022, with U.S. Vice President Kamala Harris visiting the Philippines, that country’s navy accuses China’s coast guard of seizing debris from a suspected Chinese rocket that landed in Philippine waters.

Less than a year after taking office, Philippine President Ferdinand Marcos Jr. welcomes an expanded U.S. military presence on the island nation. The four additional military bases in the northern Philippines will more than double the previous number, expanding the United States’ presence in the South China Sea. Chinese officials raise strenuous objections to the move while Philippine diplomats confront their Chinese counterparts over accusations that China’s navy has repeatedly used lasers to harass Philippine and Australian sailors. The following month, as President Xi begins an unprecedented third term as China’s leader, Beijing announces a 7.2 percent increase in military spending, citing “escalating” threats.

The trilateral summit comes days after U.S., Australian, Japanese, and Philippine forces conducted their first-ever four-way joint naval patrols in the Philippines’ EEZ. In their leaders’ statement, they highlight China’s recent aggressive moves in the South China Sea and express concern with its increased patrolling in the East China Sea, where the Japan-administered Senkaku/Diaoyu Islands are located. On April 28, China’s Coast Guard confronts Japanese lawmakers conducting an inspection mission in the East China Sea.