South China Sea disputes
June 29, 2025
The South China Sea is a site of overlapping territorial claims, geopolitical competition, and a crucial part of the world economy.
Its seabed holds large reserves of crude oil and natural gas, the exploration of which is complicated by disputes.
Trillions of dollars worth of trade flows through the South China Sea every year.
The sea connects major East Asian economies like China, Japan, and South Korea with Europe, Africa, and the rest of Asia.
The disputes involve 6 countries (China, Vietnam, Indonesia, Malaysia, Philippines, and Brunei) as well as Taiwan (not recognised by most countries) but also increasingly involve external actors, like the United States.
Why is the South China Sea disputed?
The United Nations Convention on the Law of the Sea (UNCLOS) is the main international agreement that governs maritime law.
Exclusive Economic Zone (EEZ): Area of the sea/ocean where countries get exclusive rights to fish, drill, and explore, covering an area up to 200 nautical miles from their coast.
EEZs are highly desirable since they are a source of fishing as well as undersea oil drilling and mining.
This is different from territorial waters, which only extend 12 nautical miles. This is the area where a country keeps full legal authority.
Despite the 200 nautical mile limit, China claims most of the sea, arguing that it extends from various islands that it also claims.
The roots of the disputes go to the 1940s when China’s Nationalist leader Chiang Kai-shek announced an “11-dash line” during the Chinese Civil War.
Following the Communist victory in the war, Mao Zedong slightly changed the claim into a “9-dash line”.
Territorial claims were mostly dormant until the 1970s when oil and gas reserves were discovered in the South China Sea.
The growing significance of the region made the disputes more relevant in the 21st century.
2016 Hague Ruling: An international tribunal ruled in favour of the Philippines against China’s claims, though the Chinese government rejected this.
China has embraced a variety of so-called “grey zone tactics,” in which it takes small steps to slowly strengthen its claims and control. These include:
Creating artificial islands: added more than 3,200 acres of new land through land reclamation.
Maritime militia: Using fishermen and commercial vessels as a paramilitary force while avoiding direct military conflict.
Coast Guard blockades: preventing foreign ships from entering disputed areas.
Diplomatically, the Chinese government prefers to resolve maritime territorial disputes with individual states.
China has pointed to the fact that it has managed to find peaceful solutions to most of its land border disputes this way.
Other governments worry that they will be too weak to negotiate with China single-handedly and instead prefer negotiating as a group.
China is the biggest trading partner of all the countries disputing its claims while ASEAN as a bloc is China’s biggest trade partner.
In 2024, bilateral China-ASEAN trade reached $982 billion, making sanctions costly for both sides.
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Flashpoints and Incidents
Clashes in disputed waters have become more frequent, risking an escalation into armed conflict.
2014: Chinese ships rammed into Vietnamese vessels that were trying to prevent the installation of a Chinese oil rig.
2024: Chinese Coast Guard fired a water cannon at a vessel from the Philippines near the Chinese-controlled Scarborough Shoal.
Southeast Asia’s Response
Because countries have different interests, their positions towards China’s claims vary.
Following the 2016 Hague ruling, the new Filipino president Rodrigo Duterte moved away from relying on international courts, hoping to resolve the dispute bilaterally.
Duterte was elected on a populist, tough-on-crime platform, and was open to better relations with China.
Duterte’s presidency was marked by a violent war on drugs, which included executions without trial by police and unknown vigilantes.
The drug war operations have resulted in thousands of civilians killed, as Duterte urged the public to kill drug-dealers and addicts.
Since 2025, Duterte has been held by the International Criminal Court awaiting trial for crimes against humanity.
Duterte’s successor moved closer to the United States in an effort to protect the Philippines’ territorial claims, including by reopening US military bases in the country.
The current Philippine president is the son of a long-time dictator who was a close US ally.
Vietnam has increased investments in its military while developing stronger partnerships with a wide range of countries, including both the United States and Russia.
Vietnam continues to integrate economically with China, despite political concerns, while also staying firmly outside any formal alliance system.
During the Cold War, Vietnam fought against both the United States and China, making it wary of getting too close to any foreign power.
Growing US-China tensions has led some countries to move part of their manufacturing to Vietnam in an effort to reduce risk by diversifying supply chains.
Paradox: this made Vietnam more attractive to countries wanting to reduce exposure to China while also boosting China-Vietnam trade.
Malaysia, Brunei, and Indonesia have kept a lower profile in the disputes compared to other countries in the region.
ASEAN does not have a common position on the South China Sea disputes.
Its decisions require mutual agreement, which promotes harmony but makes reaching a decision harder.
Some ASEAN members, such as Cambodia and Laos, do not have any territorial disputes with China and wish to keep good relations with their large neighbour.
The region’s growing significance as well as worsening China-Western relations have led to outside parties becoming more present in the South China Sea.
The United States, the United Kingdom, and France have all engaged in “freedom of navigation operations”.
The stated purpose: to ensure that ships can freely sail in international waters while pushing back against China’s maritime claims that contradict international law.
China views these operations as an effort to constrain it militarily.
Possible Futures
Without any immediate and comprehensive solutions to the various disputes, the future is still uncertain.
De-escalation: A Code of Conduct could be signed between ASEAN countries and China to reduce the risk of confrontations that could spiral out of control.
Frozen conflicts: Occasional clashes but without a full-scale war.
Possible war: US-China tensions could continue to escalate.
The United States’ mutual defence treaty with the Philippines along with its military bases in the region and growing US-China rivalry could also turn a local dispute into a global conflict.
Another potential source of conflict could be Taiwan, where the Taiwanese authorities reject Chinese control while the mainland government asserts that Taiwan is a part of China.
Should a war break out in Taiwan, it could grow into a larger regional conflict that includes the South China Sea.
Author Naman Habtom, PhD
Editor Anton Kutuzov
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