Why does China want the South China Sea?

In the realm of geopolitics, few regions have garnered as much attention and intrigue as the South China Sea. Bordered by several Southeast Asian nations and encompassing a maritime expanse of over 1.3 million square miles, this ocean holds a pivotal role in current international relations. For many decades, China has claimed sovereignty over roughly 90% of it — to the detriment of several smaller neighbors. At the heart of the matter lies an intriguing question: Why does China — a populous, powerful and economically successful nation — harbor such a fervent interest in the South China Sea?

Historical claims

Historical records indicate that Chinese mariners were among the first to navigate the waters of the South China Sea. The maritime routes through this sea were part of the ancient Silk Road — a network that connected China to Southeast Asia, the Indian subcontinent, the Middle East, and Africa. This connection was integral to the exchange of goods, ideas, and cultures, and it also helped to settle Chinese merchants in a slew of other countries. The Qing Dynasty treated the Silk Road mainly as a commercial route rather than a base for overseas power projection, because it was relatively self-sufficient and its ideology discouraged aggressive territorial expansion.

Beijing’s modern argument turns those voyages into a sovereignty narrative: commercial memory, old routes, and repeated maritime use can be presented together as evidence of a political relationship with the water itself. In that reading, trade, settlement, fishing and navigation become components of a national story in which China portrays itself as a long-standing maritime actor whose present claims recover an older regional role.

Beginning in 1839, however, China would be gradually compelled to open itself up to the world. At that time, the Opium Wars introduced European Imperialism to the country and marked the onset of a period that came to be known as the “Century of Humiliation”. As the Qing Dynasty faltered and the Western powers imposed their wishes, China momentarily retreated from the world stage. The glories of its past, including maritime ones, remained part of Chinese political memory.

More recently, the Chinese Communist Party has made it a priority to demonstrate that the state has “historical rights” to the South China Sea. According to the party line, a nation can claim sovereignty over a territory if it can demonstrate a continuous and long-standing historical connection to it. In domestic political terms, this argument also links maritime policy to national rejuvenation: recovering influence over adjacent waters is framed as a correction of weakness, not merely as an expansion of present-day power.

That helps explain why historical language remains politically useful even when legal arguments are contested abroad. If the sea is described only as a collection of shipping lanes, the dispute looks like a bargaining problem among coastal states. If it is described as part of China’s interrupted national story, however, compromise becomes harder, because concessions at sea can be portrayed domestically as concessions over recovery, dignity and territorial completeness.

One of the key documents often cited is a map from the Ming Dynasty, dating back to the 14th century, which shows a “nine-dash line” encompassing the majority of the South China Sea. This line demarcates the area where China has a long-standing presence, by way of fishing and navigation. The Chinese government, with the help of scholars and intellectuals, asserts that this map is proof that China can legitimately rule over its bordering sea. For neighboring states, however, the same logic is deeply controversial, because a historical claim over routes and fishing grounds can collide with modern maritime borders, exclusive economic zones and rival memories of use.

Economic interests

Although the ancient Silk Road ceased to be active several centuries ago, the shipping lanes in the South China Sea are increasingly important. International trade is the lifeblood of the modern Chinese economy, that exports competitive and technologically-advanced goods. About a third of the world’s shipping takes place within the South China Sea, yet the waters are not controlled by any single state. This puts China at the mercy of other countries and of their willingness to allow the liberty of navigation. That is why enforcing supremacy over the sea is paramount to preventing disruptions to the flow of trade.

From Beijing’s perspective, this is not an abstract shipping concern. Factories, ports, energy imports and export markets all depend on predictable sea lanes, so control over nearby waters is treated as a way to reduce vulnerability in the same system that made China wealthy. Even if merchant ships continue to sail freely in ordinary times, Chinese planners have reason to worry about what could happen during a diplomatic crisis, a naval confrontation or a conflict around Taiwan.

Another critical aspect of the South China Sea is its abundance in fisheries. It is one of the world’s most important fishing grounds, accounting for around 12% of the total fishing catch. China, with its vast population and growing middle class, has a voracious appetite for seafood. In addition, this sector is a vital source of employment and income for millions of people. Most recently, overfishing in its nearby waters has led China to expand its fishing operations into the contested regions of the South China Sea, exacerbating tensions with its neighbors. The fishing issue also blurs the line between economics and sovereignty, because boats that pursue catch in disputed waters can become symbols of national presence as well as private economic activity.

Finally, there have been sea disputes rooted in the region’s potential for oil and natural gas exploration. While estimates vary, many experts believe that the region contains significant reserves. In 2016, for instance, the US government believed there were 11 billion barrels of oil and 190 trillion cubic feet of natural gas available — enough to supply China for a long time.

Today, state companies such as the China National Offshore Oil Corporation (CNOOC) already have deepwater drilling projects in operation — both within China’s exclusive economic zone and within areas that are contested. Controlling the South China Sea reduce the country’s dependence on foreign energy supplies, what is crucial for its energy security. Taken together, trade routes, fisheries and offshore energy explain why the dispute is so persistent: the sea contains a bundle of economic interests that reinforce one another.

The vulnerability is sharper when the South China Sea is placed on the wider map. Ships carrying energy from the Gulf and goods toward global markets must move through narrow passages before they reach Chinese ports, especially the Strait of Malacca. In a severe crisis, those passages could become pressure points rather than neutral corridors. That is why Beijing invests not only in ships, but also in overland pipelines, friendly ports and diplomatic influence around Southeast Asia: the aim is to make Chinese trade harder to interrupt at any single maritime chokepoint.

This does not mean China can simply command the sea without cost. Smaller claimants depend on the same waters for food, revenue and legal rights, while outside powers treat freedom of navigation as a test of the maritime order. The economic argument therefore cuts in two directions. It explains why China wants more control, but it also explains why neighbors resist a settlement that would make their own access depend on Chinese tolerance.

Strategic interests

Besides having enormous economic potential, the South China Sea is crucial to China’s military defense. It serves as a buffer zone between the country and the Pacific Ocean, securing important parts of the coast — such as Hong Kong and the major industrial hubs of Guangdong and Shenzen. Were China to engage in a conflict over the status of Taiwan, for instance, it would be very beneficial to have a secure southern flank, isolating the Taiwanese Navy from the rest of the Pacific. In this sense, the same geography that carries trade also shapes military planning, because sea control affects how quickly ships, aircraft and supplies can move.

The strategic problem is larger than the immediate coastline. Between China and the open Pacific sits the island chain that includes Japan, Taiwan and the Philippines. Chinese strategists often see this geography as a barrier that can limit naval movement in wartime, while U.S. alliances and partnerships give Washington influence near many of the same passages. From Beijing’s perspective, a stronger position in the South China Sea widens the room for Chinese forces to maneuver before they reach the wider Pacific or the Indian Ocean.

The military component of Chinese policy towards its adjacent waters is more than clear when taking into account the “artificial islands” that China has been building. These islands, built on top of reefs and submerged ocean features, serve multiple purposes. On the one hand, they bolster China’s territorial claims by physically marking its presence in the region. On the other hand, they also serve as military outposts in which runways, ports, and support facilities provide operational value. Their operational value builds through accumulation: a runway, a harbor, a radar site and a regular patrol pattern together turn distant reefs into practical instruments of state power.

It is certainly possible to use these islands for mere defensive purposes, by policing the shipping lanes, ensuring the legality of fishing expeditions, and preventing other global powers from setting a foothold in the South China Sea. But the same facilities can also support pressure against other claimants, which is why neighboring governments view them with suspicion. For China, they extend surveillance and response capacity; for others, they make Chinese power more permanent, more visible and harder to ignore in waters that remain disputed.

However, several neighboring countries fear the potential for Chinese offensives against their waters and their interests in the high seas. Indeed, it is not uncommon to hear about Chinese warships intimidating, or even attacking, other countries’ fishing boats. Sometimes, these warships perform dangerous maneuvers even against other countries’ Navy vessels, building up tension and resentment.

In 2016, following two years of judicial procedures, an arbitral tribunal ruled in favor of the Philippines, in a maritime dispute against China. The judges concluded that Chinese historical claims to sovereignty over the South China Sea are unfounded and inadmissible, according to the United Nations Convention on the Law of the Sea (UNCLOS) — the treaty that currently regulates the seas of the world. Nevertheless, China has persistently rejected this binding ruling and has continued its military build-up in the South China Sea.

That refusal shifts the dispute from specific rocks, reefs and maps toward a wider contest over who sets expectations for behavior at sea. If China can normalize patrols, construction and pressure without accepting the tribunal’s reasoning, the practical balance may shift even without a formal legal victory. If other states keep contesting those moves, the sea remains a place where law, diplomacy and military presence are tested every day in real time.

Conclusion

China’s claims in the South China Sea draw upon ancient maritime routes, historical documents, and concepts of sovereignty. These are the justifications that are used to account for the current interest in securing control over an area that has enormous economic potential and that is key to both defending China and projecting its power. Tensions flare up, however, because other countries also want to exploit their share of the sea.

Along with the status of Taiwan, the geopolitics of the South China Sea is one of the issues that can potentially lead to a large-scale conflict in the Asia-Pacific. It also fits into China’s broader foreign policy. The dispute is also one of the main tests for U.S. foreign policy in the Indo-Pacific, because freedom of navigation, alliance credibility and crisis management all meet in the same waters. Therefore, much attention must be devoted to tracking the military movements in the region and making sure countries have a way to de-escalate their disputes. Over the vast expanse of the sea, eventual skirmishes can provoke a spiral of retaliations between countries. For that reason, states need channels for compromise before retaliatory cycles become a full-scale war.

The harder those channels are to maintain, the more a local incident can expose the larger problem: trade, energy security and military access are now tied together in one crowded maritime space.