US Commission warns Chinese gray zone tactics threaten Pacific cables

The US-China Economic and Security Review Commission released its September 2026 report warning that Chinese gray zone tactics targeting undersea cables put major US security and economic interests at risk, with Google and Meta trans-Pacific cable projects ranking among those most exposed to deep-sea sabotage.

The London-based China Strategic Risks Institute produced the report under contract. The report’s authors built an interactive index, called the Trans-Pacific Cable Gray Zone Vulnerability Index, that ranks undersea cables most at risk and displays Pacific Ocean routes. Its measurements include undersea depth, nearby shipping traffic, who owns each cable, and China’s exclusive economic zone and its territorial claims. The index also treats a cable’s link to Taiwan as a risk factor.

Taiwan describes itself as a self-governing island democracy, though China claims the island. China has sent more warships and aircraft on maneuvers around Taiwan in recent years. The commission argues that China’s growing cable disruption abilities endanger major US security and economic interests, especially for first-island chain countries.

The commission made the index to help policymakers grasp cable risk profiles and set priorities for monitoring and patrols. PLA strategists increasingly point to undersea cables as a weakness to defend, an intelligence tool, and a possible target for offensive action. Beijing applies military-civil fusion to build dual-use tools that improve access to undersea cables and targeting of them.

The operational Striver submersible, rated for 10,000-meter depths, and swarming uncrewed platforms called Haiyi serve as examples. Technologies still under development include hibernating cable cutters meant to be placed on adversary infrastructure ahead of time. Beijing’s undersea cable ambitions have been a strategic priority since at least 2014. China also seeks to achieve Command of the Deep Sea as the undersea domain grows more critical to its economic and national security.

Cable systems linking the United States to Taiwan, Japan, and the Philippines rank among the most exposed trans-Pacific routes because of Beijing’s maritime claims, shallow waters, and heavy shipping. Both current systems and planned new ones face these exposures. Connections from the continental US to Hawaii and Guam are especially vulnerable because redundancy options are few.

A cut to one cable could swamp direct routing capacity between the United States, Taiwan, Japan, and the Philippines, pushing traffic onto slower paths. If multiple cables are cut at once, trans-Pacific capacity could be overwhelmed, sending US-Indo-Pacific communications around the world by other routes. Small delays in latency can cause serious harm to high-frequency traders, AI services, and other US economic interests that depend on fast connections.

The United States should cooperate with allies on shared maritime domain awareness platforms and more cable patrols. It should also back joint incident response protocols and tougher penalties along with exclusion zones near vulnerable areas. Washington should help allies modernize fleets that are aging and thinly stretched while stockpiling critical equipment ahead of time.

Subsea fiber-optic cables stretching 1.2 million kilometers carry more than 99 percent of the data traffic between continents. Around 500 active submarine fibre-optic cables carry more than 95 percent of the world’s communications, cloud traffic, and financial transfers between continents. They move terabits of information per second, while satellites manage only one gigabit per second. Financial institutions conduct an estimated 22 trillion dollars in transactions per workday over these cable systems.

Amazon, Google, Meta, and Microsoft own or lease around half of all undersea bandwidth. Private content providers including those firms hold nearly 50 percent of the world’s undersea bandwidth. The four companies also fund and control roughly 90 percent of new capacity across the Atlantic.

SubCom, Alcatel Submarine Networks, Nippon Electric Company, and HMN Technologies together manufacture and install about 98 percent of the world’s undersea cables. HMN Technologies, once called Huawei Marine Networks Co., Ltd, is headquartered in China and receives state subsidies.

The Office of the Director of National Intelligence says cable landing stations face high-risk national security threats from cyber attacks, vandalism, and foreign influence. If cable landing stations are breached, China could reroute and throttle data traffic, including traffic for US-based services.

China’s Digital Silk Road initiative, driven by state-backed firms including HMN Tech and China Unicom, seeks to capture 60 percent of the global cable market. A planned EMA cable costing 500 million dollars would link Beijing to emerging markets in Africa, Southeast Asia, and Latin America. China already holds patents on technology meant to sever cables.

On Aug. 8-9, 2026, two cables failed in quick succession off Perth, Australia near a vessel industry observers considered suspicious. On Aug. 9, 2026, a Chinese-flagged research vessel hovered directly above the Pacific Light Cable Network, an 8,000-mile fiber-optic system linking Taiwan, the Philippines, and the United States.

Only one cable-repair vessel, owned by UAE-based e-Marine, operated in the Persian Gulf in May 2026. Some cable cuts in a conflict zone could overstretch limited cable repair ship capacity and leave countries or regions offline for weeks or months.

Seventeen submarine cables run through the Red Sea alone and carry most data traffic between Europe, Asia, and Africa. Seven or more commercial submarine cable systems cross the Strait of Hormuz, among them AAE-1 and SEA-ME-WE 5. A Houthi missile strike hit a vessel sometime from 2024 to 2025, dragging its anchor and damaging several Red Sea cables.

In May 2026, media outlets tied to the IRGC said undersea cables crossing Iranian-controlled Persian Gulf waters ought to face Iranian regulation. Subsea cables make high-value, low-cost targets for asymmetric warfare, and a commercial trawler or shadow-fleet tanker dragging a modified anchor could disrupt them.

Most undersea cable damage results from accidents like nets dragged by trawlers and anchors pulled by ships across the seabed. Storms and undersea landslides also damage undersea cables. Analysts warn that Russia and China use cable sabotage or tampering as gray zone tactics below the level of direct military confrontation. Chinese research ships have devoted an extraordinary amount of time to apparently surveying undersea cables, and Chinese commercial ships are under investigation for cutting cables in waters off Europe and Asia.

A Chinese fishing vessel and a cargo ship were blamed for cutting two cables to Taiwan’s Matsu Island in early 2023, though Taiwan officials stopped short of calling the cuts intentional. Taiwan has long said China deliberately cuts its cables through grey zone tactics, while China says the cuts were maritime accidents. The Matsu cuts kept 14,000 residents off the internet and interrupted texts, bill payments, businesses, and e-commerce.

Over a March 22 weekend, reports said China developed a ship capable of cutting cable lines at depths up to 4,000 meters. That ship came from the China Ship Scientific Research Centre and its State Key Laboratory of Deep-sea Manned Vehicles. Taiwan has held war games including internet blackouts resulting from undersea cable disruptions. Washington has barred HMN Tech and other Chinese infrastructure providers from landing on allied territories, pushing Beijing to create alternative submarine routes through the Red Sea corridor.