China has built a 3,200-hectare network of island military bases in the South China Sea, some of which are now capable of launching nuclear bombers, intelligence reveals.
The latest satellite images tracked by the Asia Maritime Transparency Initiative at the Center for Strategic and International Studies (CSIS) show the true extent of China's rapid expansion across the region.
Gregory Poling, director of the Asia Maritime Transparency Initiative, said the base development was alarming for Australia and regional allies like Japan and the US.
"China has a lot of military infrastructure on these bases now," Mr Poling told the ABC.
"They include: harbours, large runways, more than 72 fighter jet hangars across three big island bases, surface-to-air missile and anti-ship cruise missile emplacements, and a lot of radar, sensing and communications infrastructure.
"These bases are the result of the quickest example of mass dredging and landfill in human history."
China now has 20 outposts in the Paracel Islands and seven in the Spratly Islands.
Four of those are fully operational naval and air bases.
Nuclear-capable bombers now 'within range of Australia'
Imagery captured in May this year, and first reported by Reuters, revealed the deployment of two Chinese H6K nuclear-capable bombers on Woody Island, in the Paracel Archipelago.
Dr Abdul Rahman Yaacob, a research fellow at Lowy's South East Asia Program, said the bases were "extremely concerning" for Australia.
"These are long 3,000-meter runways that China has built, clearly with the intent to deploy advanced H6K bombers. These bombers can launch missiles within range of Australia."
"Three of the bases in the Spratly island chain are now capable of landing those bombers, too," he told the ABC.
China also controls Scarborough Shoal, which it seized in 2012, via a constant coast guard presence.
"China is trying to turn the area into a Chinese lake," Dr Yaacob said.
China's island-building spree
China considers the islands to be a legitimate extension of its territory, claiming historic rights to the South China Sea.
According to the United Nations and international law, the bases are unlawful.
That is a position that the Australian government backs. The Department of Foreign Affairs and Trade says China's conduct in the South China Sea is "deeply concerning."
China occupied virtually zero dry land in the South China Sea at the start of the 2010s.
"Since then, China has created seven military bases on the Spratly Islands, 800 or so miles [1,300 kilometres] from mainland China's coast, some of which have airstrips and deepwater ports," Mr Poling said.
CSIS analysis of one of those bases, at Mischief Reef, shows combat aircraft hangars, missile shelters and high-frequency radar systems.
It is a level of detail that provides a clearer understanding of China's capabilities in the region.
"China can see and hear and communicate across the whole South China Sea in a way that nobody else, including the United States, can," Mr Poling said.
"One of the bases could hold all of the United States's Pearl Harbour Naval Base in its lagoon, and almost all of Washington DC can fit inside the lagoon at Mischief Reef."
The South China Sea is one of the world's most contested locations, where more than $3 trillion of trade passes through each year.
"What was an occasional point of friction between China and its neighbours has now become a 24-hour-a-day, seven-day-a-week campaign of coercion. It's made possible by that island-building spree," Mr Poling said.
China has had a presence in the Paracel Islands Chain since the late 1950s.
It then took up its first outpost in the Spratlys in the late 1980s.
"But these were tiny bases … think of pillboxes on stilts," Mr Poling said.
"China can now see and hear pretty much everything that takes place in the South China Sea. It's an impressive capability."
The team Mr Poling leads has been documenting the island build-up for the last decade.
They have published their findings online. It reveals the scale and capability that China has developed.
It is not just China that has been building bases in the South China Sea.
Vietnam is also rapidly building bases in response to China.
Five nations occupy nearly 70 disputed reefs and islets spread across the South China Sea.
Besides China, they are Vietnam, the Philippines, Malaysia and Taiwan.
They have built more than 90 outposts on these contested features.
"These countries, particularly in South East Asia, are pushing back, with some success, against China's coercive tactics," Mr Poling said.
"But China clearly has an upper hand.
"It's actually closer to Australian territory than it is to Chinese territory at its southernmost end."
Brunei also lays claim, but has not built bases on the reefs.
China's Nine-Dash Line a dangerous 'fantasy'
China lays claim to territory in the South China Sea according to what is known as the "nine-dash line".
China's Communist Party created the nine-dash line map in 1953.
The nine-dash line refers to a line consisting of nine dashes depicted in various official and unofficial Chinese maps.
It extends off the coast of China's Hainan Island and runs close to the coast of Vietnam, deep into the South China Sea, enclosing the Spratly Islands.
"The dash line is a revisionist historical fantasy by China's Communist Party, but that doesn't make it any less dangerous," Dr Yaacob said.
"What we have seen is that these historical narratives can have real-world consequences, look at Russia's idea of Ukraine belonging to its territory and what has happened there with a full-scale invasion."
Countries, including Australia, have been conducting freedom of navigation exercises in the region with allies like Japan.
In 2023, Australian Navy Divers were injured when a Chinese warship deployed strong sonar pulses.
China has also deployed military-grade lasers against Royal Australian Air Force aircraft, which risk blinding pilots.
'Great Wall of Sand' an environmental disaster
China and Vietnam have destroyed thousands of acres of coral reefs due to base building in the South China Sea, according to the US Government and the CSIS.
The means and methods China has employed to construct so many bases in such a short span have relied upon a specialised sea-dredging technology.
The artificial islands were created by dredging sand onto reefs, which were then concreted to make permanent structures.
Large vessels hoover up coral reefs and then churn that material indiscriminately, providing the sand for the islands.
"It's complete indiscriminate destruction," Mr Poling said.
"China has destroyed more than 4,000 acres of reef in the Spratly and Paracel Islands, which it has covered over. It's severely destroyed at least another 20,000 acres of the seabed and reefs that it's dug up to make the sand.
"That is easily, and there's not even anything comparable, the most egregious intentional destruction of coral reefs in human history."
The destruction of the coral reefs led to the then-US Pacific Fleet commander, Admiral Harry Harris, to coin the island chains China's "Great Wall of Sand".
A US government report found that China's dredgers deposited sand and gravel on top of about 13 square kilometres of coral reefs, a process that destroys the coral underneath.
Frank E Muller-Karger, professor of biological oceanography and remote sensing in the College of Marine Science at the University of South Florida, explained that in the process of island building, the sediment deposited on the reefs "can wash back into the sea".
"This could form plumes that can smother marine life and could be laced with heavy metals, oil, and other chemicals from the ships and shore facilities being built."
One study estimated that China (65 per cent) and Vietnam (33 per cent) were behind 98 per cent of all coral reef destruction in the South China Sea.
