Earlier this year (2025), Taiwan’s Ministry of Economic Affairs released an Assessment Report on Taiwan–Philippines Power Cooperation, which examined the feasibility of transmitting renewable electricity back to Taiwan via submarine power cables. However, the assessment focused primarily on technical specifications and cost considerations, with limited attention to broader security risks. The Energy Security and Climate Resilience Research Program at DSET emphasizes that, in light of recent incidents—including repeated damage to undersea communication cables by the PRC, as well as the suspected Russian sabotage of the Estlink 2 submarine power cable connecting Estonia and Finland in December 2024, which led to a surge in domestic electricity prices—the importance of assessing the construction and operational risks of submarine power cables has become increasingly evident.
Against this backdrop, DSET’s Energy Security and Climate Resilience Research Program published the report Vulnerabilities at Depth: Submarine Power Cable Sabotage and Supply Chain Risks Amid China’s Rise in October this year. The report examines supply chain security threats facing submarine power cables, explores risks of sabotage, legal and policy gaps, and China’s growing industrial influence within global supply chains driven by its manufacturing capacity. It further puts forward five key policy recommendations each for the Taiwanese government and the international community, urging greater awareness of the systemic risks posed by overreliance on China-manufactured critical submarine cable components, and calling for enhanced international technological and regulatory cooperation to address vulnerabilities in the protection and monitoring of submarine power cables.
Key Conclusions and Recommendations
Building upon the content bought by DSET’s previous report discussing addressing inherent challenges in safeguarding Taiwan’s undersea communication cables against gray zone activities, this report urges attention not only to communication cables but also to submarine power cables, which face heightened vulnerability. Beyond shared threats from gray zone activities, power cables suffer from technical and supply chain gaps, including even lower redundancy and maintenance capacity, and other technical and supply chain gaps. Furthermore, they receive less regulatory protection than communication cables and may even fall outside the scope of critical infrastructure regulations.
Submarine power cables also face long-term, comprehensive challenges: Accelerated market demand from the energy transition has spurred growth in long-distance transmission projects, leading to extended procurement cycles and order backlogs. Against this backdrop, China—leveraging its catching-up technology in IGBTs (key components) and excess production capacity—has heightened the risk of growing systemic over-reliance in the global high-voltage direct current (HVDC) transmission market.
This study uses case studies to illustrate how China has developed three distinct models to dominate the submarine power cable market: “technology equity participation,” “overseas investment by state-owned enterprises,” and “acquisition of local companies,” rapidly expanding its market share in the international cable interconnection market.
The report recommends:
- Recognize Submarine Power Cables as Critical Infrastructure
Governments must explicitly include submarine power cables within critical infrastructure protection acts. This classification enables stronger regulatory safeguards, routine inspections, and preventive measures, shifting from reactive recovery to proactive resilience. Lessons from the EU, Japan, and the U.S. demonstrate the effectiveness of embedding cable protection into broader critical infrastructure governance.
- Establish Regional Maintenance and Repair Hubs
Governments should strengthen regional collaboration by establishing strategic maintenance and repair hubs. Pooling resources through agreements like the Atlantic Cable Maintenance Agreement and the Asia Pacific Marine Maintenance Service Agreement provides shared access to vessels, spare parts, and skilled personnel. Developing such hubs into advanced centers for training, diagnostics, and component manufacturing would shorten repair timelines, reduce economic losses, and enhance collective security across interconnected grids.
- Diversify Supply of Critical Components
Long-term resilience requires diversification of supply chains for submarine cables and critical components such as IGBTs. While short-term reliance on Chinese suppliers may be unavoidable, overdependence poses systemic risks. Governments should support local and allied manufacturing, incentivize joint ventures, and embed supply chain risk assessments into procurement policies. For Taiwan, this means bolstering domestic manufacturers, leveraging its semiconductor ecosystem for IGBT production, and engaging in international standardization efforts to strengthen both supply security and export competitiveness.
Report link: https://dset.tw/en/research/vulnerabilities_at_depth-2/
