China Expands Offshore Drilling Near Pratas, Raising Legal and Security Risks for Taiwan

Large energy installations deepen the dispute near Dongsha

At least a dozen oil and gas structures and support vessels linked to China National Offshore Oil Corporation have been operating inside or near the exclusive economic zone Taiwan claims around Pratas, also known as Dongsha, in the northern South China Sea. Satellite images and maritime tracking from July and August 2025 show an industrial presence that combines resource exploration with growing pressure on waters Taipei says fall under its jurisdiction.

One structure approached within about 50 kilometers of the restricted waters around Pratas. Separate equipment movements in 2024 came within roughly one kilometer of the boundary. A platform identified as NanHaiErHao, or Nanhai No. 2, moved deep into the area, reaching roughly 30 miles from the restricted waters line.

The activity had attracted little public attention until an analysis assembled positions and timelines from public tracking information and satellite imagery. Many of the locations were subsequently validated. By September 6, 2025, the picture was of a sustained presence, with some Chinese assets operating in and around Taiwan's claimed zone since at least May 2020.

Taiwan's presidential office has demanded an immediate halt. Beijing presents offshore exploration as a response to energy needs and a defense of its claimed rights. Between those positions sits a practical problem for Taipei: large installations can remain at sea for years, while the government faces limits on enforcement and access to international dispute settlement.

Regional security scholars describe such activity as greyzone pressure, meaning actions below the level of open combat that gradually change conditions on the ground or at sea. Around Pratas, the concern is that repeated industrial operations could make Chinese presence seem routine in waters where Taiwan says permission is required.

What the offshore network contains

The latest tracking tally identifies 12 permanent or semi permanent structures inside or near Taiwan's claimed exclusive economic zone around Pratas: seven rig structures, three floating production storage and offloading vessels, and two platforms of the semi submersible type. The floating vessels can handle and store hydrocarbons, while other installations support drilling or production.

Steel foundations called jackets have been planted on the seabed at several locations. Jackets support wellhead platforms and can stay in place for years. Their installation points to operations with a much longer presence than a passing survey ship.

Several wellhead platforms rank among Asia's largest. At least one vessel in the area is more than 240 meters long, with a deck comparable in area to one and a half football fields. The scale matters for enforcement: these are enormous pieces of industrial equipment, with the ability to extract, store or support the handling of oil and gas.

The Jamestown Foundation's research found that Chinese assets typically staged from Daya Bay in Guangdong. Their movements accelerated during the summer of 2025. The combination of established structures and new deployments has increased the extent of activity in an area where Taipei requires prior permission for artificial islands, installations and other structures.

How the buildup developed

Jamestown's analysts, who track maritime behavior, traced a pattern extending across several years. Their findings place the recent summer movements within a longer period of Chinese operations around Taiwan's claimed zone.

• May 2020: Chinese assets were present in and around the claimed zone by at least this month.
• 2024: Separate movements brought equipment within roughly one kilometer of the restricted waters boundary around Pratas.
• July and August 2025: Satellite and maritime tracking identified at least a dozen assets linked to CNOOC, with movements accelerating during the summer.
• September 6, 2025: The buildup had become a public legal and security issue, with Taipei calling for the activity to stop.

The Jamestown research team warned that a limited public response could help make the deployments an accepted feature of the maritime environment:

The failure to protest today risks normalizing sovereignty shaving and encourages further encroachment.

The phrase describes a gradual process: individual moves may fall short of a major confrontation, while their combined effect reduces the space in which Taiwan can exercise its claimed authority.

What the law of the sea says

The United Nations Convention on the Law of the Sea, known as UNCLOS, gives coastal states sovereign rights to explore, exploit, conserve and manage natural resources within an exclusive economic zone extending up to 200 nautical miles from their baseline. Those rights cover resources such as offshore oil and gas.

Foreign ships retain freedoms of navigation and overflight in an exclusive economic zone. Resource extraction is different: another state needs the coastal state's consent to exploit oil or gas there. Operating rigs without that consent challenges the coastal state's jurisdiction.

Taiwan's political status complicates its options. Taipei is outside the United Nations and the UNCLOS arbitration mechanisms, limiting access to formal dispute settlement even when conduct appears to breach the convention. Domestic law also leaves gaps concerning which parts of the claimed zone the government chooses to enforce.

The 2016 South China Sea arbitration ruling rejected expansive maritime claims, including China's nine dash line. Beijing rejects that ruling and continues to assert sweeping claims across the sea. The disagreement around Pratas therefore combines competing maritime positions with Taiwan's restricted access to international legal processes.

Why Taiwan's response has been difficult

Taiwan's coast guard says it tracks maritime targets within its surveillance area. It also says oil exploration and commercial cooperation lie outside its enforcement responsibilities. That division leaves a practical problem over which institution should lead a response to industrial activity in contested waters.

The size of the installations adds another difficulty. Monitoring a platform, protesting its presence and compelling it to leave require very different resources. Specialists say the division of responsibilities and the scale of the equipment make challenges at sea hard to mount.

Bonnie Glaser, managing director of the Indo Pacific program at the German Marshall Fund in Washington, suggested that Taiwan's capabilities and competing demands could explain the limited response:

My guess is that Taipei lacked capabilities to respond, and that explains why they did not. Perhaps they underestimated how extensive it would be.

Taipei's presidential office has taken a public position against the deployments, accusing Beijing of violating international norms and damaging regional stability and the international order established around the law of the sea:

We call on Beijing to immediately stop illegal deployment and exploitation activities in regional economic waters including ours. This behavior violates international legal norms and undermines regional stability.

Energy needs and China's claimed rights

CNOOC describes itself as one of the world's largest independent exploration and production companies. Its international joint ventures have included past projects with Taiwan's state energy company, CPC. CNOOC is also state owned and aligned with Beijing's political priorities, placing its offshore operations at the intersection of business and state policy.

Chinese officials and scholars present exploration near Pratas as serving energy demand while defending what China regards as its rights in adjacent waters. Zhu Feng, a professor at Tsinghua University's center for international security and strategy, described resource needs as the main impetus, rather than an effort to escalate tensions rapidly:

China's oil and gas exploration is primarily driven by its current energy needs and reflects a strong stance in safeguarding its claimed rights and interests in the region.

CNOOC's former chairman Wang Yilin used more strategic language in a 2012 speech. He described large offshore rigs as:

mobile national territory and a strategic weapon

The two explanations show why the same platform can carry economic and political weight. It can support hydrocarbon production while establishing a durable presence in an area where governments dispute who has the right to authorize that work.

How energy platforms could support security operations

Fixed platforms and steel jackets offer potential mounting points for sensors, communications equipment and logistics facilities. Analysts warn that such structures could carry radar for detecting vessels, electro optical equipment, systems for collecting signals and acoustic gear for underwater monitoring.

Helipads can support frequent landings. Small caliber weapons or defenses against nearby aerial threats could also be added if Beijing chose to strengthen selected sites. Whether any particular platform will receive those systems has not been established in the account of the buildup.

Jamestown's assessment argues that offshore infrastructure can provide some of the jurisdictional and operational effects of island building at far lower cost. A network of installations could help monitor shipping lanes, complicate resupply to outposts such as Pratas, and provide staging or replenishment points for coast guard vessels and maritime militia during a crisis.

The concern is therefore broader than drilling alone. Installations near the approaches to Taiwan's southwestern sea lanes could improve China's ability to observe maritime traffic and support enforcement operations if tensions rise.

Past confrontations show the wider regional stakes

Offshore structures have been drawn into conflict before. Britain built sea forts during World War II to defend approaches to the Thames. In the late 1980s, Iran used offshore platforms to support its forces during the Tanker War, prompting United States strikes.

China's earlier rig deployments inside waters claimed by Vietnam also triggered crises. Hanoi repeatedly protested and at times used aggressive tactics at sea to interfere with Chinese rigs. Those efforts helped bring about withdrawals on more than one occasion. Around Taiwan, by contrast, offshore assets have remained for years with limited public challenge.

Japan faces a related dispute in the East China Sea. Tokyo says China has positioned 21 drilling structures near the maritime boundary, despite a framework for joint development agreed about a decade earlier that remains frozen. Japan worries that drilling could draw gas from underground reservoirs extending into the Japanese side.

Beijing rejects Tokyo's criticism and says its drilling occurs in areas under Chinese jurisdiction. Vietnam has also condemned Chinese tenders and previous rig placements overlapping waters it claims. Together, the disputes show how resource development can become a means of pressing maritime claims.

The Vietnamese experience is part of the argument for a more persistent response around Pratas. Analysts advocating coordination say sustained public objections, monitoring and diplomatic statements can make it harder for contested deployments to become routine.

Taiwan's fuel dependence adds another pressure point

Taiwan imports nearly all its fuel and relies heavily on liquefied natural gas, or LNG, for electricity generation. Its last operating nuclear reactor closed in May 2025, increasing reliance on gas, coal and oil.

LNG supply depends on ships arriving regularly. Storage on the island covers weeks rather than months, leaving planners to manage a supply chain with little room for prolonged interruption. A blockade that prevented fuel carriers from docking would put electricity supply under immediate strain.

Recent wargames conducted by the Center for Strategic and International Studies suggested Taiwan could exhaust available gas in roughly 10 days under a blockade. Coal stocks could last about seven weeks and oil about 20 weeks. Modelers warned that electricity output could fall to one fifth of its level before a blockade if ships could not enter port.

Those estimates show the different buffers available for each fuel: gas would run out far sooner than coal or oil in the modeled scenario. They also explain why activity near southwestern shipping approaches attracts attention beyond the immediate question of drilling rights.

The installations near Pratas could support surveillance and enforcement during a crisis. Rising tensions can also unsettle energy markets and insurers, potentially increasing Taiwan's import costs. For Taipei, the issue joins maritime jurisdiction with the practical need to keep fuel arriving.

What Taipei and regional partners could do

Policy proposals range from formal protests to more visible operations at sea. Taiwan could publish evidence packages documenting installation sites through commercial satellite images and maritime tracking, including information from sensors that work in all weather. Regular publication would give the public and other governments a clearer record of changes.

Clarifying responsibilities among the coast guard, navy and energy regulators could address gaps in enforcement. Carefully increased patrols around Pratas could demonstrate Taiwan's claimed jurisdiction while seeking to avoid collisions. Proposals also include personnel from partner countries aboard patrol vessels, or joint patrols, to increase visibility and diplomatic weight.

Japan, Vietnam and the Philippines are identified as possible partners for diplomatic coordination. Joint statements and continued monitoring could frame the deployments as a shared regional concern rather than a dispute Taipei must manage alone.

Taiwan could also work with friendly governments to consider targeted restrictions on CNOOC's access to finance, technology or port services if rigs remain without consent. These are policy ideas, rather than announced measures. They would need to be combined with crisis management and a consistent approach to treating energy infrastructure as both an economic and a security issue.

Lin Chao lun, an associate research fellow at Taiwan's Institute for National Defense and Security Research, called for coordinated action and warned about the cost of accepting the drilling:

Without firm countermeasures against drilling near Dongsha, sovereignty will be gradually eroded.

The immediate choice for Taipei is how to turn its objections into sustained monitoring, clear institutional responsibility and coordinated pressure. The longer the structures remain, the more they shape expectations about who can operate in these contested waters.

The Bottom Line

• Tracking identified at least 12 CNOOC structures and support assets inside or near Taiwan's claimed exclusive economic zone around Pratas, with one structure about 50 kilometers from restricted waters.
• Chinese assets have operated in and around the zone since at least May 2020. Equipment movements in 2024 approached within roughly one kilometer of the restricted waters boundary.
• The tally includes seven rig structures, three floating production storage and offloading vessels, and two semi submersible platforms.
• Taiwan has demanded a halt, while limited access to international dispute settlement, divided enforcement responsibilities and the size of the installations complicate its response.
• China presents the work as serving energy needs and defending claimed rights. Analysts warn that platforms could also support surveillance, logistics and coercion.
• Japan has protested 21 Chinese drilling structures in the East China Sea. Vietnam's previous protests and actions at sea helped secure rig withdrawals.
• Taiwan's fuel dependence increases the stakes. Blockade wargames estimated roughly 10 days of available gas, seven weeks of coal and 20 weeks of oil.
• Proposed responses include public evidence, formal protests, clearer agency responsibilities, measured patrols and coordination with regional partners.