Executive Summary
This report examines the security threats to submarine power cables with a focus on sabotage risks, legal and policy gaps, and China’s growing influence in the supply chain. Drawing on interviews and case studies in the Taiwan Strait and the Baltic region, the report highlights vulnerabilities in protection and monitoring while underscoring the risk of systemic over-dependence on China.
1. Rising Security Threats to Submarine Power Cables
Incidents of deliberate or accidental submarine cable damage are growing, with profound implications for energy security and regional stability. While submarine telecommunications cables have attracted global attention, submarine power cables remain comparatively underexamined despite their longer repair times, higher costs, and wider economic consequences.
The sabotage of the Estlink 2 interconnector during the 2024 Christmas period illustrated these vulnerabilities. Estonia’s average electricity price surged from €75.5/MWh in February 2024 to €184/MWh in February 2025, while direct damages were estimated at €50 million. Import capacity fell from 1,016 MW to 358 MW, forcing reliance on domestic oil shale and gas-fired generation. This case underscores how disruption of power cables can destabilize national energy markets, impose heavy costs on consumers, and undermine regional security resilience.
2. Technical Constraints and Repair Bottlenecks
Submarine power cables are uniquely vulnerable due to their lack of redundancy, high installation costs, and demanding technical requirements. Unlike telecom cables, they cannot easily reroute capacity when disrupted. Global repair capacity is extremely limited: of roughly 60 cable repair vessels in operation, only a small fraction can handle high-voltage power cables. Long-distance missions require specialized ships with heavy lifting gear, advanced onboard systems, and strict safety standards.
This scarcity creates a critical bottleneck in emergency response. Multipurpose vessels capable of laying both power and telecom cables are exceedingly rare, leaving outages vulnerable to prolonged delays. Limited repair capacity thus constitutes not only a technical constraint but also a strategic vulnerability for interconnected energy systems.
3. Jurisdictional and Policy Gaps
Protecting submarine power cables is complicated by significant legal and policy constraints. Under current international law, if damage occurs beyond a state’s territorial sea, coastal authorities lack clear jurisdiction to act against the offending vessel. This limitation hampers timely intervention and weakens the pursuit of legal accountability.
Jurisdictional ambiguity is further compounded by the “flag of convenience” problem, as vessels operating under foreign flags make it even more difficult for affected states to assert prosecutorial legitimacy.
At the national level, many countries have yet to formally include submarine power cables within the scope of critical infrastructure protection. This policy gap not only leaves cables under-protected but also diminishes the political priority needed to mobilize resources for their defense.
4. China’s Expanding Role in Supply Chains
Global manufacturers face rising costs, prolonged procurement cycles, and record backlogs in submarine cable production. Lead times for procurement now extend two to three years, while direct current cables for long-distance transmission often take over five years from order to delivery. Against this backdrop, China’s rapidly expanding share in overseas interconnector markets raises the risk of systemic over-dependence.
The case of Ningbo Orient Wires & Cables Co., Ltd. (Orient Cable) illustrates how coordinated national and local policies have systematically fostered the growth of China’s submarine cable industry. Since the 11th Five-Year Plan, Beijing has scaled R&D, manufacturing, and service capabilities through targeted investments, enabling Chinese firms to meet surging domestic demand and strengthen their global competitiveness.
Beyond cables, China has also advanced in critical components such as insulated-gate bipolar transistors (IGBTs) which now represent around 40% of global demand. Domestic producers have achieved significant technological progress in grid-scale IGBTs and leveraged this capability to reinforce China’s competivity ㄏleadership in high-voltage direct current (HVDC) systems. By achieving self-sufficiency and increasingly shaping global technical standards, China has positioned itself as an indispensable actor in the resilience and governance of submarine power infrastructure. Domestic producers have achieved significant technological progress in grid-scale IGBTs and leveraged this capability to reinforce China’s competiviteness in high-voltage direct current (HVDC) systems. By achieving self-sufficiency and increasingly shaping global technical standards, China is establishing itself as an indispensable actor in the resilience and governance of submarine power infrastructure.
Policy Recommendations
1. 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.
2. 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.
3. 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.
Scope of the Report
This report provides an in-depth analysis of the strategic, industrial, and security dimensions of submarine power cable infrastructure, which have become critical assets linking clean energy development, industrial localization, and national security.
Chapter 1 outlines the strategic context and policy framework for Taiwan’s submarine power cable development. This chapter highlights how power cables have shifted to a strategic infrastructure central to energy resilience and national security.
Chapter 2 maps the regional industrial landscape and supply chain dynamics of submarine cable manufacturing, installation, production capacity, market concentration, and the rise of PRC-based suppliers in both export and domestic projects.
Chapter 3 analyzes geopolitical risks and sabotage vulnerabilities associated with submarine cables. It reviews recent global incidents, emerging patterns of gray-zone activities, and the reactions and limitations of Taiwan’s response.
Chapter 4 delves deeper into China’s rise and dominance in the submarine cable supply chain. Through case studies, it illustrates specific patterns and provides a detailed analysis of why these risks must be taken seriously, as well as how to respond to China’s growing influence.
Chapter 5 provides consolidated policy recommendations. It proposes a multi-layered strategy—encompassing technological, regulatory, and industrial dimensions—to secure submarine power cables as critical infrastructure, not only for the Taiwanese government but also the broader international context.
Acknowledgments
DSET extends its sincere appreciation to all interviewees for their invaluable contributions to this research. The findings and recommendations presented in this report reflect the views of DSET alone and do not represent the positions of the interviewees or any government agency.
