China is carrying out oil and gas exploration inside Taiwan’s exclusive economic zone (EEZ), according to new research that analysts say reflects Beijing’s strategy of steadily eroding Taipei’s control over its territory.
At least 12 vessels and permanent structures operated by the state-owned China National Offshore Oil Corporation (CNOOC) were detected in Taiwan’s EEZ during July and August, including one within 50km of the restricted waters around the Taiwan-controlled Pratas Islands. Several steel foundations for offshore drilling platforms were also identified, according to research by the US-based Jamestown Foundation.
The activity, which has not previously been reported, is viewed by experts as part of China’s “greyzone” tactics, non-military actions designed to advance territorial claims without triggering direct conflict. Beijing claims Taiwan as a province and the entirety of the South China Sea, despite a 2016 ruling at The Hague rejecting its maritime claims.
“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 Jamestown report warned that Taipei’s apparent lack of response risked normalising China’s encroachment. “Failure to protest today risks normalising sovereignty shaving and encourages further encroachment,” it said.
Some of the assets are substantial, including a vessel more than 240 metres long and two of the largest wellhead platforms in Asia. The report said some platforms had been present for years, with one positioned within a kilometre of Pratas in 2024.
Analysts noted that Taiwan lacks the military capability and legal mechanisms to challenge the activity. It is not a party to the UN Convention on the Law of the Sea (Unclos), and its domestic legislation on EEZ enforcement remains unclear.
“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 programme at the German Marshall Fund.
Taiwan’s authorities have largely declined to comment. The coast guard said it continued to monitor maritime activity but that oil exploration fell outside its remit. The national security council and ocean affairs council both declined to respond to questions.
CNOOC, one of the world’s largest oil and gas firms, has joint ventures with foreign companies, including Taiwan’s CPC. However, officials in Taipei said no active contracts are currently in place. The company has previously described its deep-water rigs as “mobile national territory and a strategic weapon”.
Beijing has denied suggestions that the activity is provocative. Zhu Feng, a professor at Tsinghua University’s centre for international security and strategy, said it was “primarily driven by its current energy needs” but reflected China’s firm stance on safeguarding its claimed rights.
Neighbouring countries have raised similar concerns. Japan this week accused China of positioning 21 drilling rigs inside its EEZ in the East China Sea, in what Tokyo described as a unilateral attempt to develop disputed gas fields.
The Jamestown report also warned that the structures could be adapted for military purposes, including surveillance or blockades, heightening fears that they may form part of Beijing’s long-term preparations for coercion or invasion.
Beijing has intensified military drills, coast guard patrols and incursions around Taiwan in recent years, steadily increasing pressure on Taipei’s defences. Analysts say that faced with growing provocations, Taiwan may be choosing to remain silent to avoid drawing attention to its inability to act.
“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,” said Powell.
