China is drilling for oil and gas inside Taiwan’s exclusive economic zone (EEZ), a move that analysts believe is likely part of Beijing’s unilateral grab for disputed territory that could also aid a future invasion of Taiwan.
During July and August at least 12 oil and gas vessels and permanent structures were detected inside Taiwan’s EEZ – including one within 50km of the restricted-waters border of the Taiwan-controlled Pratas Islands – as well as several steel supports for fixed offshore drilling platforms, called jackets. Their presence inside Taiwan’s EEZ have not been previously reported.
Experts said the activity fit the pattern of Beijing’s “greyzone” strategies for seizing disputed territory. Beijing claims the entirety of the South China Sea, despite The Hague ruling the claim unlawful in 2016. Beijing also claims Taiwan is a province of China, and in preparation to forcibly annexe it has ramped up a campaign of “salami slicing” Taiwan’s territory, forcibly shrinking the space that Taipei can control and defend.
“China’s greyzone aggression routinely leverages commercial activity for expansionist goals,” said Ray Powell, director of SeaLight, a maritime transparency project at Stanford University.
The presence of Chinese vessels and structures in the EEZ was first identified in research published on Tuesday by US thinktank the Jamestown Foundation, which said they were owned by the state-run China National Offshore Oil Corporation (CNOOC).
However, there is no sign of the Taiwan government having responded to it, despite frequently enforcing its EEZ elsewhere.
The apparent lack of response has surprised analysts. “Failure to protest today risks normalising sovereignty shaving and encourages further encroachment,” the Jamestown report warned.
The assets are large – including at least one vessel measuring more than 240m long with decks equivalent to 1.5 football fields, and two of the largest wellhead platforms in Asia. The report found some had been there for at least five years, with one coming within a kilometre of the Pratas restricted-waters border in 2024. The Guardian has independently located most of the assets using civilian maritime tracking websites.
Challenging the oil and gas activity in Taiwan’s EEZ would be difficult. Taiwan’s political status meant it is not party to the UN convention on the law of the sea (Unclos) or its arbitration mechanisms. Domestic law about which parts of the EEZ border Taiwan enforces is unclear and it does not have the maritime strength to challenge such activity.
“My guess is that Taipei lacked capabilities to respond, and that explains why they didn’t,” said Bonnie Glaser, managing director of the Indo-Pacific program at the US-based German Marshall Fund.
“Perhaps they underestimated how extensive it would be.”
CNOOC describes itself as “one of the largest independent oil and gas exploration and production companies in the world”. It engages in numerous joint ventures with foreign firms, including with Taiwan’s CPC, although Taiwan’s ministry said there are currently no active contracts.
But as a state-owned firm, it also works in the interests of Beijing’s political ambitions. In 2012, CNOOC’s chair, Wang Yilin, said in a speech: “Large-scale deep-water rigs are our mobile national territory and a strategic weapon,” according to the Wall Street Journal.
CNOOC was approached for comment.
Prof Zhu Feng, from the Tsinghua University’s centre for international security and strategy, said China’s oil and gas exploration was “primarily driven by its current energy needs” and was not intended to further escalate territorial disputes.
“Rather it reflects China’s strong stance in safeguarding its claimed rights and interests in the region,” Zhu told the Guardian.
Such activity has previously drawn the ire of other governments.
This week Japan’s government accused Beijing of positioning 21 drilling rigs inside the Japanese EEZ, in an alleged “unilateral” effort to develop gas fields in disputed waters of the East China Sea and potentially extract gas from the Japanese side.
The Jamestown report warned that structures like the jackets also had potential for dual use by China’s military, and “could facilitate a full range of coercion, blockade, bombardment and/or invasion scenarios against Pratas or Taiwan more generally”.
In the five years since these assets were first moved into the EEZ, Beijing has ramped up a campaign to weaken Taiwan’s control over its territorial space, with military drills and incursions, and coast guard patrols in the restricted waters around Taiwan’s offshore islands.
“China has been steadily overwhelming Taiwan’s defences with aggressions much nearer their shores, which may make this something they’d simply rather not have to deal with,” Powell said.
“Often governments don’t publicly respond to aggressions if they think making such complaints would beg the question of what else they can do about it.”
The Guardian contacted Taiwan’s national security council for comment. It also contacted the ministry of economic affairs, which referred most questions to Taiwan’s ocean affairs council. The council declined to comment. Taiwan’s coast guard said it “maintains continuous monitoring of maritime targets within its surveillance area” but that oil drilling exploration and cooperations were outside its remit.
China’s ministry of foreign affairs did not respond to a faxed request for comment.
