China has built a land-based prototype nuclear reactor for a large surface warship, in the clearest sign yet Beijing is advancing toward producing the country’s first nuclear-powered aircraft carrier, according to a new analysis of satellite imagery and Chinese government documents provided to The Associated Press.

China’s navy is already the world’s largest numerically, and it has been rapidly modernizing. Adding nuclear-powered carriers to its fleet would be a major step in realizing its ambitions for a true “blue-water” force capable of operating in seas far from China in a growing global challenge to the United States.

“Nuclear-powered carriers would place China in the exclusive ranks of first-class naval powers, a group currently limited to the United States and France,” said Tong Zhao, a senior fellow at the Carnegie Endowment for International Peace in Washington, D.C. “For China’s leadership, such a development would symbolize national prestige, fueling domestic nationalism and elevating the country’s global image as a leading power.”

Researchers at the Middlebury Institute of International Studies in California said they made the finding while investigating a mountain site outside the city of Leshan in the southwest Chinese province of Sichuan, where they suspected China was building a reactor to produce plutonium or tritium for weapons.

Instead they concluded that China was building a prototype reactor for a large warship. The project at Leshan is dubbed the Longwei, or Dragon Might, Project and is also referred to as the Nuclear Power Development Project in documents.

Neither China’s Defense Ministry nor Foreign Affairs Ministry responded to requests for comment.

Satellite images and public documents helped identify likely carrier project

There have long been rumors that China is planning to build a nuclear-powered aircraft carrier, but the research by the Middlebury team is the first to confirm that China is working on a nuclear-powered propulsion system for a carrier-sized surface warship.

“The reactor prototype at Leshan is the first solid evidence that China is, in fact, developing a nuclear-powered aircraft carrier,” said Jeffrey Lewis, a professor at Middlebury and one of the researchers on the project. “Operating a nuclear-powered aircraft carrier is an exclusive club, one that China looks set to join.”

Drawing on satellite images and public documents including project tenders, personnel files, environmental impact studies — and even a citizen’s complaint about noisy construction and excessive dust — they concluded a prototype reactor for naval propulsion was being built in the mountains of Mucheng township, some 70 miles (112 kilometers) southwest of Sichuan’s provincial capital Chengdu.

The reactor, which procurement documents indicate will soon be operational, is housed in a new facility built at the site known as Base 909, which houses six other reactors that are operational, decommissioned or under construction, according to the analysis. The site is under the control of the Nuclear Power Institute of China, a subsidiary of the China National Nuclear Corporation, which is tasked with reactor engineering research and testing.

Documents indicating that China’s 701 Institute, formally known as China Ship Research and Design Center, which is responsible for aircraft carrier development, procured reactor equipment “intended for installation on a large surface warship” under the Nuclear Power Development Project as well as the project’s “national defense designation” helped lead to the conclusion the sizable reactor is a prototype for a next-generation aircraft carrier.

Satellite mages from 2020 to 2023 have shown the demolition of homes and the construction of water intake infrastructure connected to the reactor site. Contracts for steam generators and turbine pumps indicate the project involves a pressurized water reactor with a secondary circuit — a profile that is consistent with naval propulsion reactors, the researchers say.

An environmental impact report calls the Longwei Project a “national defense-related construction project” that is classified “secret.”

“Unless China is developing nuclear-powered cruisers, which were pursued only by the United States and the Soviet Union during the Cold War, then the Nuclear Power Development Project most certainly refers to a nuclear-powered aircraft carrier development effort,” researchers wrote in a detailed 19-page report on their findings shared exclusively with the AP.

Jamie Withorne, an analyst at the Oslo Nuclear Project who was not involved in the research and reviewed the findings, said Middlebury’s team made a “convincing argument.”

“From the identifying reports, co-location with other naval reactor facilities, and correlating construction activity, I think it can be said that it is likely the Longwei Project is housed at Base 909, and it could potentially be located at the identified building,” she said.

The research does not, however, provide clues as to when a Chinese nuclear-powered carrier could be built and become operational, she said.

Sarah Laderman, a senior analyst with Open Nuclear Network, a program of the US-based NGO PAX sapiens foundation, said the findings were “carefully conducted and thoroughly researched.”

“Given the evidence presented here, I see a compelling case made that China seems to be working towards building a nuclear propulsion system for its naval surface ships (likely aircraft carriers) at this location,” said Laderman, who is based in Vienna and was not involved in Middlebury’s research.

Pursuit of a nuclear-powered carrier

China’s first carrier, commissioned in 2012, was a repurposed Soviet ship, and its second was built in China but based upon the Soviet design. Both ships — named the Liaoning and the Shandong — employ a so-called “ski-jump” type launch method, with a ramp at the end of a short runway to help planes take off.

The Type 003 Fujian, launched in 2022, was the country’s third carrier and its first to be indigenously designed and built. It employs an electromagnetic-type launch system like those developed and used by the US Navy. All three carriers are conventionally powered.

Sea trials hadn’t even started for the Fujian in March when Yuan Huazhi, political commissar for China’s People’s Liberation Army Navy, confirmed the construction of a fourth carrier. Asked if it would be nuclear-powered, he said at the time that would “soon be announced,” but so far it has not been.

There has been speculation that China may begin producing two new carriers at once — one Type 003 like the Fujian and one nuclear-powered Type 004 — something that it has not attempted before but that its shipyards have the capacity to do.

Matthew Funaiole, senior fellow at the Center for Strategic and International Studies’ China Power Project, said he doubts China’s next carrier will be nuclear-powered. Instead, he said, he would expect the People’s Liberation Army Navy’s fourth carrier to focus on optimizing the existing design of the Fujian carrier with “incremental improvements.”

Nick Childs, senior fellow for naval forces and maritime security at the International Institute for Strategic Studies, said the Chinese “have taken an incremental approach to their carrier development with a number of ambitions that will evolve over time.”

“For now, their deployments have been relatively cautious, remaining largely within range of shore support, but projecting influence and to some extent coercion within their near waters.”

Eventually, however, “larger carriers more akin to their US counterparts will give them more options to project power,” Childs said.

It takes several years to build a carrier and bring it into operation, but developing nuclear propulsion for its next generation of warships would eventually give China more power to run advanced systems, such as electromagnetic launchers, radars and new technology weapons, Childs said.

“As well as obviating the need for the ship to refuel regularly and therefore giving it much greater range, nuclear power means that without the need to carry fuel oil for the ship there will be room aboard for fuel and weapons for its aircraft, extending their capabilities,” Childs said.

“Much will depend on what overall size the next carrier is, but the addition of nuclear power will represent a significant step further in China’s carrier development with a vessel more comparable to the US Navy’s carriers.”

Zhao, of the Carnegie Endowment for International Peace, said nuclear-powered carriers would provide the Chinese military “with greater flexibility and endurance to operate around strategic hotspots, especially along the First Island Chain, where most territories disputed by China are located,” said Zhao.

The First Island Chain includes the self-governed island of Taiwan, which China claims as its own and vows to annex it by force if necessary.

The US is obligated by a domestic law to supply Taiwan with sufficient weapons to deter invasion, and it could provide assistance to the island from its bases in the Pacific in the event of an invasion or blockade. Tensions also have risen in the South China Sea between China and neighboring nations over territorial disputes and maritime claims.

“These carriers could also extend Chinese operations deeper into the Western Pacific, further challenging the US military’s ability to ‘intervene’ in regional matters that China views as best resolved by countries from the region only,” Zhao said.

US-China rivalry

Chinese President Xi Jinping has tasked defense officials with building a “first-class” navy and becoming a maritime power as part of his blueprint for the country’s rejuvenation.

The country’s most recent white paper on national defense, dated 2019, said the Chinese navy was adjusting to strategic requirements by “speeding up the transition of its tasks from defense on the near seas to protection missions on the far seas.”

The People’s Liberation Army Navy is already the world’s largest navy with more than 370 ships and submarines. The country also boasts powerful shipbuilding capabilities: China’s shipyards are building many hundreds of vessels each year, whereas the US is building five or fewer, according to a US congressional report late last year.

However, the Chinese navy lags behind the US Navy in many respects. Among other advantages, the US currently has 11 carriers, all nuclear powered, allowing it to keep multiple strike groups deployed around the world at all times, including in the Indo-Pacific.

But the Pentagon is growingly increasingly concerned about China’s rapid modernization of its fleet, including the design and construction of new carriers.

That aligns with China’s “growing emphasis on the maritime domain and increasing demands” for its navy “to operate at greater distances from mainland China,” the Defense Department said in its most recent report to Congress on China’s military.

And China’s “growing force of aircraft carriers extend air defense coverage of deployed task groups beyond the range of land-based defenses, enabling operations farther from China’s shore,” the report said.