China's Man-Made Islands in the South China Sea Are Sinking: A Strategic Gamble Unraveling

The South China Sea is one of the most strategically and economically significant bodies of water on the planet, carrying up to one-third of global maritime traffic and goods worth an estimated three trillion dollars annually. It is also the arena for one of the most contentious territorial disputes of the modern era — one in which the People’s Republic of China has taken the extraordinary step of dredging artificial islands from the seafloor, militarising them with advanced weapons systems, and asserting sovereignty over vast swathes of contested ocean. But China’s ambitious island-building project is now facing a convergence of problems: international legal rejection, diplomatic backlash from nearly every neighbouring state, shoddy construction materials, and perhaps most damning of all, the relentless forces of nature. The man-made islands that Beijing staked its maritime claims upon are, quite literally, sinking.

Why the South China Sea Matters So Much

The South China Sea’s importance cannot be overstated. It connects some of the most significant maritime trade routes in the world, linking major ports including Manila, Singapore City, Kuala Lumpur, Ho Chi Minh City, and Taipei. The volume of cargo transiting through these waters is thought to account for up to one-third of all global maritime traffic, carrying goods valued at up to three trillion dollars each year. Whoever controls the South China Sea effectively holds leverage over this colossal flow of commerce.

Beyond trade, the sea is a treasure trove of natural resources. It is responsible for an estimated 12% of the entire world’s annual fishing catch despite comprising only about 2% of the globe’s total sea volume, making it one of the most abundant fishing grounds on Earth. Beneath the surface, the sea is thought to contain approximately 11 billion barrels of oil and 190 trillion cubic feet of natural gas, though the true extent of these reserves remains uncertain because territorial disputes have left the area chronically underexplored.

It is this potent combination of trade dominance, fishing wealth, and hydrocarbon potential that has transformed the South China Sea into a flashpoint for competing national interests. The countries with claims to the area include China, Indonesia, Malaysia, the Philippines, Brunei, Vietnam, and Taiwan — but it is China that has pursued the most aggressive strategy to establish outright sovereignty.

The Spratly Islands and the Nine Dash Line

China’s strategic presence in the South China Sea is anchored around two island groups: the Paracel Islands in the north and portions of the Spratly archipelago further south. The Spratlys are the primary source of contention. Located roughly 1,000 kilometres from mainland China and approximately 960 kilometres from its nearest uncontested territory, the islands sit far closer to the coastlines of the Philippines, Vietnam, and Malaysia. The Philippine island of Palawan, in particular, lies almost within reach of some of the smallest Spratly islets.

Despite this geographic reality, China bases its sweeping claims on a document known as the Nine Dash Line. This map first appeared in 1946, originally as an eleven-dash line conceived not by the People’s Republic of China but by the Republic of China — Taiwan’s predecessor state. The original map incorporated roughly 90% of the South China Sea’s maritime territory, including various islands and half of the Gulf of Tonkin separating China and Vietnam.

After the Chinese Communist Party defeated the Kuomintang and established the PRC, Mao Zedong dropped two dashes from the map to avoid antagonising Vietnam, with whom China was cultivating closer ties. The Nine Dash Line was born.

China’s justification for the map largely hinges on claims of Chinese civilisational presence in the area stretching back millennia, supported by circumstantial evidence such as recovered artefacts and obscure, difficult-to-translate texts. However, some observers have dismissed the existence of these ancient civilisations as mythological. Regardless, the Nine Dash Line has become deeply embedded in Chinese national identity. As Time has described, Chinese schoolchildren are taught that the furthest extent of their territory is Zengmu in the southern Spratlys — a location roughly 80 kilometres off the coast of Malaysia that is not even an island but an underwater shoal.

Multiple other nations also occupy and have built structures on various Spratly features, including Vietnam, Taiwan, Malaysia, and the Philippines. Only Brunei, among the claimants, has refrained from construction.

How the Dispute Ignited: From Freedomland to Geopolitical Flashpoint

Though the South China Sea dispute dominates modern headlines, it did not truly ignite until the 21st century. For most of the preceding decades, the sea was regarded as a vast body of water with a few uninhabitable islands and little else of note. The seeds of the dispute, however, were planted decades earlier by an unlikely source: Filipino fishermen.

In 1947, a group of Filipino fishermen ventured near the uninhabited Spratly archipelago and discovered its extraordinary abundance of fish. One of them, Tomás Cloma, later claimed the islands as an independent micronation and his own sovereign territory. He and his companions resided on the islands, growing wealthy from the untouched fish stocks. The territory adopted the remarkable name of the Free Territory of Freedomland and existed as an unrecognised state for 18 years.

This arrangement ended in 1974 when the Philippine government recognised the islands’ fishing potential, expelled Cloma, and annexed the area. The Philippines formally declared the islands part of its territory in 1978. But by then, other players were taking notice.

China reasserted its claim to the Paracel Islands that same year, 1974, immediately constructing military installations including an airfield and artificial harbour on Woody Island, the Paracels’ largest landmass. When North Vietnam won the Vietnamese Civil War shortly after, it claimed the Paracels for itself, locking Hanoi and Beijing into a dispute that persists to this day. Relations between the two countries deteriorated so severely that they fought a month-long border war in 1979, though it produced no substantial territorial changes.

Meanwhile, the Philippines’ discovery of oil off Palawan confirmed the sea’s economic potential beyond fishing and trade. By 1992, China passed the Law on the Territorial Sea and the Contiguous Zone, formally reasserting its claim to the entire South China Sea based on civilisations it traced to the Western Han dynasty, spanning roughly 200 BCE to 9 CE. This legislation, combined with China’s broader military modernisation drive — fuelled in part by its ambition to become the world’s most potent military force by 2049, the centennial of CCP rule — set the stage for the aggressive island-building campaign that would follow.

The Hague Ruling and China’s Defiant Response

China’s claims to the South China Sea have not been well received internationally, and the backlash reached its zenith in 2016 when the Permanent Court of Arbitration in The Hague delivered a landmark ruling. The tribunal rejected the legitimacy of China’s Nine Dash Line, determining Beijing’s historical claims to be baseless and affirming the supremacy of international maritime law and the Exclusive Economic Zones of the nations party to the dispute.

The CCP reacted with fury. It rejected the court’s decision outright and doubled down on its claims. China continued to use the Nine Dash Line in all its official positioning regarding the South China Sea, expanding it back to ten dashes to accentuate its claim to Taiwan. Beijing also launched a fervent academic and educational campaign to bolster the map’s perceived validity.

More practically, China responded by pressing ahead with its island militarisation projects and accelerating its land reclamation programme. The Hague ruling, rather than constraining China’s behaviour, appeared to galvanise it.

Building Islands from the Seafloor: The Dredging Process

China’s island construction programme began taking shape by 2013, even before The Hague ruling, as engineering teams were deployed to uproot and clear away coastal reefs and mangroves on the features China occupied through a process known as dredging.

Dredging is an enormously costly and mechanically intensive process. It involves clearing away seafloor debris — and with it, marine life and natural vegetation — to establish a base for construction. China proved highly effective at this phase, cutting through vegetation at rapid speed and clearing the seafloor for the application of landfill.

The specific technique employed in the South China Sea involves slicing up the reef and then pumping sediment such as gravel and sand through pipes onto the newly cleared shallow areas. This process profoundly disturbs the seafloor, eliminating marine life and overwhelming the coral reef’s capacity to repair itself.

It is on these artificially created platforms that China transformed atolls into islands capable of supporting human habitation and infrastructure. On Woody Island in the Paracels, China constructed modern dwellings, a primary school, a bank, a hospital, and installed mobile communications infrastructure. An airport was built, and tourists have been able to visit. Communities of fishermen were established to exploit the area’s vast fishing potential.

In total, China has reclaimed and converted seven islands, creating approximately 13.5 square kilometres of new land across the Paracel and Spratly island groups.

Militarisation of the Spratlys: Far More Than Fishing Villages

While China’s developments on the Paracel Islands have included civilian infrastructure, its activities in the Spratlys carry a far more overtly military character. By 2022, China had fully militarised the three largest reefs in the Spratly chain: Subi Reef, Mischief Reef, and Fiery Cross Reef.

China has justified its construction by claiming the islands are its sovereign territory and therefore fall within its Exclusive Economic Zone, arguing that what it builds there is not anyone else’s business. Beijing has also downplayed the military dimensions, insisting the structures serve primarily economic purposes — residences for fishermen, refuges for maritime wayfarers, and similar civilian functions.

However, satellite imagery tells a starkly different story. Analysis suggests China has deployed fighter jets, cruise missiles, airfields capable of accommodating heavy-duty aerial bombers, and sophisticated radar systems. The islands have been stacked with advanced military defence systems including anti-ship and anti-aircraft missile systems, as well as laser and jamming equipment.

The so-called fishermen inhabiting the islands have also drawn scrutiny. Some analysts have concluded that the figures appearing in satellite images — nicknamed ‘little blue men’ — are actually Chinese military and naval personnel, strategically positioned to disrupt maritime trade routes and destabilise the diplomatic balance in the South China Sea.

Diplomatic Fallout: Confrontations and Regional Backlash

China’s aggressive posture in the South China Sea has generated enormous and worsening diplomatic tensions with multiple countries. The Philippines emerged as one of Beijing’s most bitter adversaries in the 1990s, when confrontations in the Spratlys nearly escalated into open conflict.

The flashpoint came in 1996 with China’s militarisation of Mischief Reef. That year, three Chinese naval vessels engaged in a brief battle with a Philippine navy gunboat near the reef — the first time China had confronted an ASEAN member other than Vietnam. The clash triggered a crisis in Sino-Philippine relations and revived military ties between the Philippines and the United States. The dispute has only intensified since, exacerbated by China’s island construction and increasingly hostile actions against the vessels of other countries, including several dangerous skirmishes with Filipino ships in recent years.

Vietnam has also been a persistent source of friction. In 2014, anti-Chinese protests erupted across Vietnam after China installed an oil rig near the Paracel Islands in a location within Vietnam’s Exclusive Economic Zone. The protests resulted in the burning of 15 Chinese-owned factories and left 21 people dead.

Even Japan, not a direct claimant to the South China Sea, has weighed in. Tokyo criticised China’s attempts to turn the sea into what it called ‘Lake Beijing,’ increased its military budget, and proposed security cooperation with the United States, India, and Australia to ‘safeguard the maritime commons stretching from the Indian Ocean region to the Western Pacific.‘

The Legal Contradictions Undermining China’s Position

China’s occasional references to the islands being part of its Exclusive Economic Zone create a legal double-edged sword. If Beijing accepts the supremacy of EEZ frameworks under international law, it must logically also accept the Hague tribunal’s ruling that its historical claims based on the Nine Dash Line are baseless.

Further complicating matters, an international tribunal declared that some of the disputed features were not legally islands at all, but rather low-tide elevations that afforded no legal entitlement to exclusive economic zones or territorial appropriation of any kind. In theory, this could work in China’s favour — if there are no islands, how can China’s construction on them be deemed a violation?

However, this interpretation cuts far more deeply against Beijing’s interests. If the features are not islands, then the applicable Exclusive Economic Zones would default to the nearest uncontested coastline, placing at least some of China’s constructions within territory belonging to the Philippines and Vietnam. It would also mean the features fall outside China’s territorial boundaries, leaving Beijing with no legal basis to object to Philippine fishing operations or American Freedom of Navigation Operations (FONOPS) — observational voyages sanctioned under international law and designed to survey and challenge excessive maritime claims.

Shoddy Construction: The Cement Problem

Beyond the diplomatic and legal quagmire, China’s man-made islands face a far more fundamental problem: they may not be structurally sound enough to last.

While China demonstrated impressive speed and efficiency in the dredging phase, serious questions have emerged about the quality of the construction that followed. As Bloomberg has reported, the cement used in the island-building projects is derived from sea sand — a material that is not particularly robust and may even cause buildings to collapse. China has used this type of cement in construction projects elsewhere, where it has also drawn criticism, but its application in the harsh and abrasive conditions of the South China Sea represents an even more acute structural risk. Buildings and infrastructure constructed with this material face the possibility of sudden collapse.

Nature Strikes Back: Why the Islands Are Sinking

Even if the construction had been carried out to the highest engineering standards, the islands might still be doomed. In its rush to assert sovereignty, China chose to battle an adversary it may simply be no match for: the force of nature.

The sea is actively eating away at China’s artificial islands. The dredging process that created them was characterised by a particular disregard for the environment, removing large swathes of flora and piling heaps of debris upon what remained. Critically, the mangroves that China obliterated during construction served as a natural brake against the ocean. Mangroves absorb tides and protect shorelines from erosion.

Without this barrier, the islands are far more exposed than normal to rising tides, which could in theory submerge them entirely.

Climate change compounds the threat dramatically. Rising sea levels endanger all islands, but the risk is especially acute for low-lying, small islands without higher elevations to which populations could retreat as coastlines erode. China’s man-made islands are simply too small and too flat for any such retreat to be possible. Some Pacific island nations have addressed similar threats by constructing sea walls — structures designed to protect areas of human habitation from tides, waves, and tsunamis.

China, notably, has not built sea walls on its artificial islands.

The environmental destruction wrought during construction has thus created a vicious cycle: the very act of building the islands destroyed the natural defences that might have protected them, leaving them uniquely vulnerable to the oceanic and climatic forces now threatening to reclaim them.

A Strategic Gamble with an Uncertain Future

China’s man-made island programme in the South China Sea represents one of the most audacious geopolitical projects of the 21st century — an attempt to literally manufacture territorial sovereignty from the seafloor. The islands have allowed Beijing to project military power deep into contested waters, deploy advanced weapons systems hundreds of kilometres from its mainland, and assert claims that the international legal community has rejected.

But the project is beset by contradictions and vulnerabilities. Diplomatically, it has united a broad coalition of regional and global powers against China’s maritime ambitions. Legally, the claims underpinning the islands have been dismissed by international arbitration. Structurally, the construction materials used may be fundamentally inadequate for the marine environment.

And environmentally, the destruction of natural coastal defences has left the islands exposed to the very ocean from which they were dredged.

The South China Sea dispute shows no signs of abating. But the question now is whether the islands at the centre of China’s strategy will even survive long enough to remain relevant to it.

Concrete Turning to Sponge: The Structural Decay Accelerating the Collapse

The structural concerns surrounding China’s artificial islands extend well beyond the initial use of sea-sand-derived cement. According to the Economist, the concrete used for land reclamation in the Spratlys has proven itself completely unfit for purpose, effectively turning into sponge in the hostile climate of the South China Sea. This degradation is not merely cosmetic — it renders the foundations of everything built upon the islands unreliable and actively undermines any capacity the structures might have had to stem rising waters.

This means that the very material intended to anchor China’s sovereign claims is instead accelerating the islands’ demise. Rather than providing a stable platform for military installations, airfields, and habitation, the deteriorating concrete is contributing to the islands’ gradual subsidence. The foundations are losing their structural integrity in real time, compounding the erosion already caused by the absence of natural mangrove barriers and sea walls. In essence, China’s useless concrete is speeding up the sinking of the islands from within, even as the ocean attacks them from without.

The result is that the islands are, as observers have noted, essentially sliding into the sea — nature reclaiming what it gave up. This represents not only a source of considerable embarrassment for Beijing but also a potentially staggering waste of the financial resources that went into creating them.

Ghost Islands: Signs of Limited Use and Strategic Hesitation

Perhaps the most telling indicator that China itself recognises the precariousness of its artificial islands is the conspicuous lack of activity on many of them. Despite the enormous investment in construction and militarisation, the islands do not appear to be particularly teeming with human life. Some of China’s military installations on the features remain rather limited in scope, and the airports constructed on the three militarised reefs — Subi Reef, Mischief Reef, and Fiery Cross Reef — showed no sign of use for several years after they had been built.

This pattern suggests that Beijing may be hedging its bets. While the islands serve an important symbolic and strategic signalling function — projecting power and asserting sovereignty on the map — China appears reluctant to commit large numbers of personnel or critical assets to structures it knows may not endure. The sparse habitation and underutilised infrastructure paint a picture of islands built more for geopolitical posturing than for sustained operational use, a reality that undermines the narrative of permanent, irreversible Chinese sovereignty over the features.

The Typhoon Threat: A Vulnerability China Cannot Engineer Away

Beyond the chronic threats of rising sea levels, structural decay, and coastal erosion, China’s man-made islands face an acute and potentially catastrophic danger: typhoons. The South China Sea is one of the most typhoon-prone bodies of water on Earth, and China does not have extensive experience in building structures designed to withstand the kinds of powerful storms that regularly sweep through the region.

The fragile structures perched atop the artificial islands — military installations, radar systems, airfields, and rudimentary civilian buildings — were not engineered with the resilience required to survive a direct hit from a major typhoon. A single powerful storm could pulverise the islands’ infrastructure, scattering debris across the reef platforms and potentially rendering the features uninhabitable in a matter of hours.

Climate change is set to make this vulnerability even more acute. As global temperatures rise, typhoons in the South China Sea are projected to become more severe, with stronger winds, heavier rainfall, and higher storm surges. For conventional islands with natural elevation and established infrastructure, such storms are devastating enough. For low-lying artificial platforms constructed from degrading concrete on dredged coral, the consequences of a direct typhoon strike could be existential.

China’s islands, in short, face a threat that no amount of military hardware or diplomatic bluster can neutralise.

The Staggering Financial Cost of Failure

While China does not publicly release detailed figures on its island-building expenditures, the financial scale of the project is believed to be enormous. It is thought that Beijing spent upwards of 12 billion dollars on its construction projects on just one island in the Spratlys — Fiery Cross Reef — alone. Extrapolated across all seven reclaimed features in the Paracel and Spratly groups, the total investment likely runs to tens of billions of dollars, encompassing dredging operations, concrete production, military hardware deployment, infrastructure construction, and ongoing maintenance.

If nature ultimately reclaims these islands — through a combination of rising seas, structural decay, erosion, and typhoon damage — the financial loss would be extraordinary. Dredging and land reclamation are among the most expensive engineering undertakings in the world, and the prospect of that investment literally sinking beneath the waves represents a fiscal misadventure of historic proportions. The sunk costs are not merely monetary; they encompass years of strategic planning, diplomatic capital expended in defending the islands against international criticism, and the reputational damage of a flagship sovereignty project visibly failing.

China’s island creation could therefore represent a kind of grand misadventure — one that proves costly both to its international prestige and to the exposed communities and military personnel it has placed on these increasingly precarious platforms.

A Convergence of Failures: Environmental, Structural, and Climatic

What makes the predicament of China’s artificial islands so remarkable is the convergence of multiple, mutually reinforcing failure modes. The environmental destruction caused by dredging eliminated the mangrove barriers that would have slowed erosion. The use of substandard sea-sand concrete produced foundations that are degrading into sponge-like material rather than hardening over time.

The absence of sea walls leaves the low-lying platforms fully exposed to tidal forces. Rising sea levels driven by climate change are steadily encroaching on islands with no higher ground to retreat to. And the increasing severity of typhoons threatens to deliver a single catastrophic blow that could obliterate structures already weakened by years of chronic decay.

Each of these problems would be serious in isolation. Together, they create a compounding cycle of deterioration that may prove impossible to reverse. China can deploy more concrete, but if the material itself is unfit for the marine environment, additional layers will simply add weight to already unstable foundations. Beijing could attempt to construct sea walls, but doing so on features already experiencing subsidence and erosion would be an engineering challenge of extraordinary difficulty and cost.

And no human intervention can halt the rise of the ocean or the intensification of tropical storms.

The artificial islands that were meant to serve as permanent, unsinkable aircraft carriers anchoring Chinese dominance over the South China Sea may instead become monuments to the limits of human engineering in the face of natural forces — expensive, strategically embarrassing relics slowly being swallowed by the very waters they were built to control.

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Frequently Asked Questions

Why is the South China Sea so strategically important?

The South China Sea carries up to one-third of global maritime traffic worth approximately three trillion dollars annually, connecting major ports including Manila, Singapore, Kuala Lumpur, Ho Chi Minh City, and Taipei. It is responsible for 12% of the world’s annual fishing catch despite being only 2% of global sea volume, and is thought to contain approximately 11 billion barrels of oil and 190 trillion cubic feet of natural gas.

What is the Nine Dash Line and why was it rejected?

The Nine Dash Line is a map that first appeared in 1946 as an eleven-dash line created by the Republic of China — Taiwan’s predecessor — claiming roughly 90% of the South China Sea’s maritime territory. After the CCP took power, Mao Zedong removed two dashes to avoid antagonising Vietnam. China bases its claims on alleged civilisational presence dating back millennia, but in 2016 the Permanent Court of Arbitration in The Hague rejected these claims as baseless and affirmed the Exclusive Economic Zones of the nations party to the dispute. China rejected the ruling outright and doubled down.

What military capabilities has China deployed on the artificial islands?

By 2022, China had fully militarised the three largest Spratly reefs — Subi Reef, Mischief Reef, and Fiery Cross Reef — deploying fighter jets, cruise missiles, airfields capable of accommodating heavy bombers, sophisticated radar systems, anti-ship and anti-aircraft missile systems, and laser and jamming equipment. Satellite imagery suggests the so-called fishermen inhabiting the islands are actually Chinese military and naval personnel positioned to disrupt maritime trade routes.

Why are the artificial islands structurally and environmentally vulnerable?

The islands face multiple compounding failure modes: the cement used is derived from sea sand and is structurally unsound, reportedly turning into sponge in the marine environment; the dredging process destroyed the mangroves that naturally protected against erosion and tides; no sea walls were constructed; and the islands are too low-lying to offer any retreat from rising coastlines. Rising sea levels driven by climate change and increasingly severe typhoons compound these structural weaknesses, creating a cycle of deterioration that may be impossible to reverse.

What is the financial scale of China’s island-building programme, and what happens if the islands fail?

China is thought to have spent upwards of 12 billion dollars on Fiery Cross Reef alone, with the total investment across all seven reclaimed features likely running to tens of billions of dollars. If nature reclaims the islands through rising seas, structural decay, erosion, and typhoon damage, the loss would encompass not only the financial investment but also the diplomatic capital spent defending the islands against international criticism — and the reputational damage of a flagship sovereignty project visibly failing.

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