New Report on China's Gray Zone Threats to Trans-Pacific Undersea Cables
The U.S.-China Economic and Security Review Commission (USCC) today released a new contracted research report, “China's Gray Zone Threats to Trans-Pacific Undersea Cables,” prepared by the China Strategic Risks Institute. The report examines China's growing capabilities to threaten critical undersea communications infrastructure and assesses the vulnerability of U.S. trans-Pacific cable networks to gray zone sabotage. It also introduces a new analytical tool—the Trans-Pacific Cable Gray Zone Vulnerability Index (GZVI)—to help policymakers identify and prioritize risks across the network.
“Undersea cables, carrying the vast majority of international data traffic, are the backbone of the global digital economy and are increasingly a matter of national security,” said Chair Randy Schriver. “This report finds that China is developing a range of capabilities to achieve ‘Command of the Deep Sea,’ with the potential to cause major disruption across these networks.”
“The cord coming into your house is the last hundred feet of a wire that crosses the Pacific,” said Vice Chair Mike Kuiken, Co-Chair of the Research Working Group. “China has built what it takes to reach that system, and it has built the cover to hide its hand while doing it. Chinese strategists write about cable networks as the spine of a seabed grid for finding American submarines. We have been treating this as a bandwidth problem, but in reality, it is a warfighting problem.”
“Protecting undersea cable networks requires more than repairing cables after they are damaged,” said Commissioner Hal Brands, Co-Chair of the Research Working Group. “To protect this critical infrastructure, the report recommends new tools to identify vulnerabilities and improve monitoring, resilience, and coordination with allies before a crisis occurs, helping ensure these critical networks remain secure and reliable.”
Key findings include:
- China is rapidly building capabilities to disrupt undersea cables: China is exploiting “military-civil fusion” to develop a range of dual-use technologies to enhance its ability to access and target undersea cables, with both legitimate civilian uses and potential offensive military capabilities. These range from 10,000-meter-class submersibles to “swarming” systems of linked uncrewed platforms.
- Key U.S. allies and partners are vulnerable to gray-zone attack: Cables connecting the United States with Taiwan, Japan and the Philippines—often crossing shallow waters, busy shipping lanes and contested waters—are among some of the most vulnerable in the trans-Pacific network. Continental U.S. connections to the state of Hawaii and the territory of Guam are also particularly vulnerable, with few redundancy options.
- Simultaneous disruption of multiple cables could overwhelm trans-Pacific capacity: Scenarios such as an attack on Taiwan could significantly reduce headroom and even overwhelm trans-Pacific capacity as a whole, forcing communications between the United States and the Indo-Pacific to re-route on longer, slower routes across the globe.
- Undersea cable disruption threatens key U.S. economic interests: Even minor slowdowns in communications latency can have major ramifications for high frequency traders, AI services, and other U.S. economic interests reliant on super-fast connections. Major disruption scenarios would have cascading impacts on the full range of U.S. economic interests in the Indo-Pacific, with tangible impacts likely on internet communications, financial services, and cloud services.
The report also offers recommendations for Congress focused on improving joint maritime domain awareness with allies, replenishing aging global cable repair fleets, and investing in undersea capabilities across the military and civil domains needed to protect critical undersea infrastructure.
The report, authored by Andrew Yeh, Zack Liao, Owen Au and Athena Tong, is available on the Commission's website here.
More than 25 years ago the bipartisan U.S.-China Economic and Security Review Commission began its work advising Congress on the economic, trade, and national security implications of the U.S.-China relationship, and providing recommendations to Congress for legislative and administrative action. Follow the Commission on LinkedIn and via @USCC_GOV on X/Twitter, Instagram, and YouTube.
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