Recently, official Chinese media and research institutions confirmed that their independently developed submarine cable cutting device has successfully completed testing at a depth of 3,500 meters in the deep sea. Analysts point out that this technological breakthrough has not only unsettled international security experts, but also poses a threat to Taiwan in the first island chain and jeopardizes the strategic security of Guam in the second island chain, according to reports.
Reported by Xinhua News Agency citing the Chinese Ministry of Natural Resources, the research vessel “Marine Geology II” completed its first deep-sea mission of the year on April 11, which included using a “deep-sea underwater electro-hydraulic actuator” to cut cables in the extremely deep sea area at a depth of 3,500 meters (approximately 2 miles).
Chinese state media claimed, “This is the first time globally that a country has publicly acknowledged the capability to cut cables at such depths in the sea, reaching depths even twice the average of existing submarine communication infrastructure.”
The device was developed by the China Ship Scientific Research Center, a group under sanctions by the United States, and its affiliated National Laboratory of Deep-Sea Manned Equipment.
This technology’s unveiling has attracted high international attention.
The South China Morning Post quoted official statements on April 15, stating that this deep-sea cable cutting device “can sever some of the world’s most secure underwater communication or power lines, potentially shaking up the global maritime power dynamic.”
American media specialist Stephen Silver issued a warning in the military journal “19fortyfive”: despite China’s claim that this device was developed for civilian salvage and deep-sea mining purposes, experts see its dual military-civilian use as evident.
Silver warned that China’s technology poses a direct threat to the strategic layout of the U.S. military in the Indo-Pacific region. Guam serves as a cornerstone of U.S. Indo-Pacific strategy and a hub in the second island chain. Its defense strategy is aimed at containing China, with over 12 fiber optic cables on the island serving private companies like Google and the U.S. military.
The South China Morning Post reported that if Beijing uses the device to cut cables near strategic anchorages, “it might cripple global communication during geopolitical crises.”
For Taiwan, the threat is even more urgent.
Hudson Institute senior researcher and former Taiwanese legislator Hsu Yu-jen testified in early March at the U.S.-China Economic and Security Review Commission on the role of submarine cables in potential conflicts.
He stated that globally, 97% to 99% of intercontinental network traffic is carried by submarine cables. He cited Chinese military documents indicating that in the event of a Taiwan Strait conflict, the Chinese military may first target the underwater cable infrastructure before invading Taiwan.
Hsu warned that the Chinese Navy could significantly reduce Taiwan’s bandwidth by cutting just three key cable clusters near the Bashi Channel, potentially reducing Taiwan’s bandwidth by 99%.
He said that this “digital blockade” would lead to military command and control confusion, financial market paralysis, public panic, and hinder Taiwan’s real-time information exchange with the international community.
According to data from George Mason University’s Mercatus Center, which highlighted several strategic points in Taiwan, including numerous submarine cable landing stations, it demonstrated that the Chinese military had conducted extensive intelligence gathering.
Hsu mentioned that China had long upgraded cable damage technology to a systematic wartime capability. Associated Chinese military organizations applied for related patents over a decade ago: in 2013, a patent for a deep-sea fiber optic cutting and recovery device; in 2022, a patent for cutting and securing both ends of a cable; in 2025, patents for underwater cutting devices and towed cutting systems.
Furthermore, the China Ship Scientific Research Center announced plans in early 2025 for an electric cutting device design capable of operating at depths of 4,000 meters. In mid-2025, China publicly unveiled a new type of submarine cable cutting ship equipped with a diamond-coated grinding wheel with a diameter of six inches and a rotation speed of 1,600 revolutions per minute, capable of piercing the toughest reinforced outer protective layers at a depth of 4,000 meters.
These developments are now considered new weapons for Beijing to disrupt global communication and order.
In addition to high-tech specialized cutting ships, China is accused of using commercial vessels to exploit international legal loopholes for gray-zone destructive actions. A report from the Center for Strategic and International Studies (CSIS) in 2025 pointed out that submarine cables had become an area vulnerable to “plausibly deniable intentional damage,” accidental severance, and interception. Beijing often attributes cable damage to accidents, but its frequency and timing raise suspicions among experts.
Report authors Erin L. Murphy and Matt Pearl mentioned that what’s even more worrisome is the formation of the “Sino-Russian gray zone axis.”
From late 2024 to early 2025, the Chinese ship “Sun Xing 39” of Chinese origin and the Russian-operated “Vasili Shukshin” were observed moving around Taiwan and near cable landing stations, indicating reconnaissance activities.
In European waters, the “Yi Peng 3” incident in November 2024 shocked the world. The Chinese vessel dragged an anchor for over 100 miles in the Baltic Sea, severing two crucial cables connecting Finland to Germany and Sweden to Lithuania.
The CSIS team believes that such actions, using “shadow fleets” and identity manipulation, provide Beijing with multiple “plausible deniability” options, assisting Russia behind the scenes while accumulating combat experience focused on Taiwan.
The submarine cable industry is primarily driven by commercial interests, with investors deciding when, where, and how to construct new cables, rather than based on national or international security needs.
China has rapidly expanded its global market share through the “Digital Silk Road” initiative. Currently, Amazon, Google, Meta, and Microsoft collectively own or lease about half of the global undersea bandwidth.
Formerly a part of Huawei, “Huahai Communications” is now the fourth-largest submarine cable construction company globally and the fastest-growing, completing over 100 projects in 78 countries.
The four major fiber optic leaders in China – FiberHome, Hengtong Optic-Electric, FiberHome Communications, and Jiangsu Zhongtian Technology – jointly control over 35% of the global market share. Beijing has set its ambition to capture 60% of the market.
In contrast to semiconductor limitations under export controls, China has the complete set of independent technologies to build and deploy cables, increasing the risk of installing eavesdropping devices (Taps), intercepting data, or implementing strategic disruption in cables during conflict.
Moreover, in the South China Sea, by asserting the Nine-Dash Line, Beijing has detained competitors’ cable project permits, forcing major cable projects by Google and Meta’s parent company Facebook to reroute.
Against the increasingly serious threats, Hsu Yu-jen proposed specific policy recommendations to the U.S. Congress, such as authorizing enhanced sanction powers, promoting updates to international conventions, setting clear damage norms, mandatory investigations, and accountability mechanisms.
He also expressed hope for U.S. funding to support the “Indo-Pacific Undersea Cable Monitoring Network” and authorize the procurement of cable repair vessels to address the shortage of military and commercial repair capabilities in Taiwan and the Western Pacific region.
CSIS experts suggested that given the vast expanse of the ocean, strengthened cooperation between government and private sectors, joint patrols with allies, funding surveillance satellites, deploying sensors on cables, and other measures are needed to form a substantial deterrence against saboteurs.
Additionally, U.S. Republican Senator John Curtis and Democratic Senator Jacky Rosen introduced the “Taiwan Undersea Cable Resilience Initiative Act” last year to protect Taiwan’s critical communication infrastructure and deter China’s malicious “gray-zone” actions.
According to the act, the Secretary of State, in coordination with the Homeland Security Secretary and Defense Secretary, should help Taiwan develop and deploy an advanced submarine cable monitoring system to instantly detect interruptions or potential damage, and in appropriate circumstances, provide Taiwan early warning of global intelligence networks.
The bill also requires the Secretary of the Navy and Coast Guard Commandant to collaborate with Taiwanese coast guard and regional allies to enhance awareness in Taiwan’s surrounding waters, focusing on detecting suspicious ships or activities near key submarine cable routes; monitoring potential threats, and preventing destructive actions.
If individuals or entities engage in activities damaging Taiwan’s national security via submarine cables, the “Taiwan Undersea Cable Resilience Initiative Act” authorizes sanctions like asset freezes or entry bans, and requires regular reports to Congress on threats and response measures.
“Beijing is intensifying its methods to isolate Taiwan, including damaging its critical submarine cables, and we should not stand idly by,” said John Curtis.
This bipartisan bill sends a clear message that the U.S. stands with Taiwan, united with our allies to defend shared infrastructure, sovereignty, and freedom.