On a cold February morning in 2025, residents of Taiwan’s Penghu Islands awoke to an unsettling silence. The whir of routers and the flow of digital communications, so ordinary as to be unnoticed, had vanished. ATMs blinked uselessly, online banking froze, and even the Taiwanese Coast Guard’s secure lines faltered. By midday, authorities traced the cause: a cargo ship, the Hong Tai, flying a Togo flag but manned by a Chinese crew, had severed one of the fiber-optic cables linking Penghu to Taiwan’s main island.^[i] The ship was impounded; its captain would later be sentenced to prison for his deliberate sabotage.^{[ii] [iii]} Yet the damage had already been done, revealing a harsh reality: beneath the waves, a new vulnerability—silent, invisible, and devastating—could be weaponized before the world even woke.

The Penghu incident was not an isolated mishap. It was a glimpse of Beijing’s evolving playbook—using undersea sabotage as a form of what scholars term gray-zone warfare.^[iv] For Taiwan, the implications are profound. Subsea cables are not peripheral infrastructure. They are the nation’s digital arteries, binding it to the world. And in a future confrontation with China, they may prove to be bothTaiwan’s Achilles’ heel and its best chance at deterrence, if defended wisely.^[v][vi]

Submerged Arteries of Resilience: Taiwan’s Subsea CableInfrastructure

Throughout Taiwan's coast, from Taipei to Yilan, Pingtung to Taitung, a few dozen major submarine cable systems converge through a handful of landing stations, carrying not only civilian internet traffic, but also financial data, emergency communications, and critical military coordination.^[vii][viii] Taiwan’s economy, security, and political resilience rest on this dense network of subsea fiber-optic cables. From these points, Taiwan connects directly toJapan, Hong Kong, Singapore, the Philippines, and across the Pacific to the United States. Google’s FASTER and Pacific Light Cable Network, Meta’s ORCA system, and a web of consortia-owned telecoms make Taiwan an indispensable node in the global internet.^[ix]

Yet this impressive infrastructure is also precarious. Many systems converge along common corridors or terminate at shared landing stations, creating concentrated points of vulnerability. In wartime, a handful of well-placed cuts could shatter the island’s connectivity, compromise market transactions, and choke military signaling.^[x] For a nation that underpins much of the world’s semiconductor supply chain,such an outcome would be catastrophic.

Echoes of the Past: Spies, Tunnels, and Taps

This is not the first era in which undersea cables have shaped geopolitical outcomes. In World War I, Britain famously severed German undersea telegram lines and tapped into others, intercepting the Zimmermann Telegram which shifted the war’s trajectory.^[xi] During the Cold War, U.S. submarines executed Operation Ivy Bells, tapping Soviet military cables under the ice of the Sea of Okhotsk to eavesdrop on naval communications.^[xii] Divers from the USS Halibut attached recorders to the cable in 1972, retrieving them monthly, a covert triumph until betrayal exposed the operation in 1981.^[xiii]

These historical precedents illustrate a constant: undersea cables are more than passive infrastructure—they are contested spaces that can inform and reshape great-power strategies. Whether through espionage or sabotage, the seabed has long been a frontier of silent struggle.

Beijing’s Gray-Zone Sabotage Campaign

In recent years, Taiwan has observed a subtle yet alarming campaign of subsea infrastructure subversion.^[xiv] In February 2023, two cables serving the Matsu Islands were cut, leaving 13,000residents offline for nearly two months.^[xv][xvi] Taiwanese officials traced the damage to vessels with links to China, but proving intent remained elusive.^[xvii] A year later, another pair of cable cuts struck the same region, this time involving both a Chinese fishing vessel and a cable ship.^[xviii][xix] Then came Penghu, an escalation captured on camera and prosecuted.

Since 2023, Taiwanese authorities have linked at least eleven such incidents to suspicious vessels, many tied to opaque affiliations.^[xx][xxi] The pattern is consistent: perpetrators sailunder flags of convenience as part of what analysts dub China’s 'shadow fleet'—vessels that appear commercial but mask hidden ownership and exhibit suspect behavior.^[xxii] Cable sabotage has emerged as a quiet weapon in this arsenal, offering Beijing plausible deniability while inflicting physical disruption and psychological strain.^[xxiii] It erodes resilience and clouds intent. Much like air incursions into Taiwan’sdefense zone or the steady presence of Chinese ships in contested waters, cable sabotage has become another instrument in gray-zone warfare—Beijing’s aggressive statecraft that stops just below the threshold of conventional war.^{[xxiv][xxv][xxvi]}

International observers have warned that these disruptions are not random accidents but rehearsals. Think tanks and intelligence assessments point to a growing willingness by China to target subsea infrastructure as a tool of coercion, just as Russia has done in the Baltic andNorth Seas.^[xxvii] The line between espionage, sabotage, and open conflict grows ever thinner beneath the waves.

Washington Steps In: Legislative and RegulatoryCountermeasures

Taiwan's predicament has not gone unnoticed in Washington. In July 2025, Senators John Curtis (R-UT) and Jacky Rosen (D-NV) introduced theTaiwan Undersea Cable Resilience Initiative Act (S. 2222), mandating a U.S. led, interagency effort to enhance monitoring, rapid response, maritime surveillance, and international cooperation against gray-zone threats targetingTaiwan’s subsea cables.^{[xxviii][xxix]}

Simultaneously, the FCC has proposed regulations to bar undersea fiber-optic connections to the U.S. that utilize Chinese-made equipment, particularly from firms such as Huawei, ZTE, and China Telecom, citing espionage and sabotage risk.^[xxx]

These initiatives underscore Washington’s strategic recognition: subsea cables are now a frontline of national and international security. Protecting them will require both hardening infrastructure and building robust incident response frameworks.

SMART Cables: A Strategic Defense Innovation

Amid this fraught environment, the concept of SMART Cables (ScienceMonitoring and Reliable Telecommunications) emerges as both shield and sentinel.^[xxxi] Developed for the purpose of environmental monitoring, such as detecting tsunamis or measuring climate change, SMART Cables embed sensors capable of detecting seismic shifts, pressure changes, and the telltale vibrations of anchors or submersibles from China’s shadow fleet.

If Taiwan had installed SMART sensors on their cables prior to the Penghu attack, Taipei would have received advanced warning of China’s actions in real time. Taiwan’s Coast Guard and Navy could have been mobilized, and vessel tracking systems could have been cross-referenced immediately, enabling interception before the cable was severed. Such visibility could deter would-be saboteurs and reduce damage. Moreover, in the fog of conflict, SMARTCables could supply the legal and evidentiary clarity needed to rally allies or impose targeted sanctions.

The implications extend further. SMART Cables integrated into Taiwan’s defense posture could form a persistent layer of maritime domain awareness, complementing radar, satellites, and undersea drones. They would not prevent every act of sabotage, but they would compress response times, bolster deterrence, and complicate Beijing’s calculus. Just as missile defenses alter the cost-benefit analysis of an attack, SMART Cables would signal to China thatTaiwan’s digital arteries are not soft targets.

International cooperation could magnify these benefits. TheUnited States, Japan, and Australia all have stakes in securing Pacific connectivity, and their naval capacities dwarf Taiwan’s.^[xxxii] Joint investment in SMART infrastructure—funded in part through public-private partnerships with the very tech companies whose cloud infrastructure depend on these cables—would not only protect Taiwan but also reinforce a collective message: that democratic nations will defend the hidden backbone of the digital economy.

Toward a Cable-Centric Defense Doctrine

The convergence of history, strategy, and technology points to a new imperative: Taiwan’s cable infrastructure must be treated as strategic national defense. This requires

• Deploying SMART Cables on high-risk routes, particularly regional chokepoints.
• Building a Subsea Cable Security Command, linking defense, intelligence, coast guard, and private operators to monitor data feeds and coordinate responses.
• Embedding cable protection in allied strategy through Quad connectivity initiatives and U.S. legislation that funds resilience projects and sanctions gray-zone actors.
• Enhancing public diplomacy by making sabotage events visible, reducing ambiguity and raising the political cost.

Conclusion

The contest over Taiwan is not confined to missiles or air defense systems. We live in an age when wars are fought on invisible battlefields. Under some of the most heavily traveled oceans in the world lies the potential for devastating disruption. Taiwan, because of its geopolitical significance, is especially vulnerable. By targeting subsea cables, Beijing is testing how much disruption Taiwan and its allies can absorb before confidence cracks.

Taiwan cannot afford to treat its cables as mere utilities.They are strategic assets, as critical as chip fabs or air defense systems. Defending them requires more than redundancy; it requires innovation. SMARTCables represent precisely that kind of innovation—a tool that fuses environmental science with national security, turning passive infrastructure into active defense.

History shows that the most decisive technologies often lie hidden until moments of crisis. In the 20th century, radar transformed air defense, nuclear submarines redefined deterrence, and satellites reshaped intelligence. In the 21st century, as the world teeters on the brink of great-power conflict, the next quiet revolution may be happening under the sea.The quieter the battlefield, the more critical it is to listen closely.

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^{[i] Business Insider. “Taiwan Detained the Hong Tai, aTogolese-Flagged Cargo Ship with a Chinese Crew, after Suspecting It ofDamaging an Undersea Cable Connecting Penghu Islands.” February 2025.https://www.businessinsider.com/nato-cable-cutting-dilemma-hits-taiwan-chinese-linked-vessel-2025-2}

^{[ii] ABC News. “The Captain, Surnamed Wang, Was Sentencedto Three Years in Prison for Severing an Undersea Cable off Taiwan.” June 13,2025.https://www.abc.net.au/news/2025-06-13/chinese-ship-captain-jailed-for-cutting-taiwan-undersea-cable/105411364
[iii] Reuters. “First: Taiwan Charges Chinese Ship Captainwith Damaging undersea Cables.” April 11, 2025.https://www.reuters.com/world/asia-pacific/first-taiwan-charges-chinese-ship-captain-with-damaging-undersea-cables-2025-04-11/
[iv] Global Taiwan Institute. “Taiwan’s DigitalVulnerabilities.” June 2025.https://globaltaiwan.org/2025/06/taiwans-digital-vulnerabilities/
[v] Taipei Times. “Feature: Taiwan’s Digital Frontlines.”July 19, 2025.https://www.taipeitimes.com/News/feat/archives/2025/07/19/2003840537
[vi] Just Security. “China’s Shadow Fleet War on Taiwan’sUndersea Cables.” 2025.https://www.justsecurity.org/113221/chinas-shadow-fleet-war-on-taiwans-undersea-cables/
[vii] University of Washington, Henry M. Jackson School ofInternational Studies. “Building Resilience in Taiwan’s Internet Infrastructurefrom Geopolitical Threats.” 2025.https://jsis.washington.edu/news/building-resilience-in-taiwans-internet-infrastructure-from-geopolitical-threats/
[viii] Ketagalan Media. “Taiwan’s Submarine Cable Network:Strategic Value and Future Outlook.” February 23, 2025.https://ketagalanmedia.com/2025/02/23/taiwans-submarine-cable-network-strategic-value-and-future-outlook/
[ix] Submarine Networks. “Taiwan Cable Landing Stations.”2025. https://www.submarinenetworks.com/en/stations/asia/taiwan
[x] Global Taiwan Institute. “Countering China’s SubseaCable Sabotage.” March 2025.https://globaltaiwan.org/2025/03/countering-chinas-subsea-cable-sabotage/
[xi] National Archives. “The Zimmermann Telegram.”https://www.archives.gov/education/lessons/zimmermann
[xii] Military.com. “Operation Ivy Bells.”https://www.military.com/history/operation-ivy-bells.html
[xiii] Dirittoue.info. “Operation Ivy Bells: Sea of Okhotsk1971–1981.”https://www.dirittoue.info/operation-ivy-bells-sea-of-okhotsk-1971-1981
[xiv] Tribune India. “US Slams China’s Strategy to CrippleTaiwan’s Communications, Pushes Back with New Legislation.” 2023.https://www.tribuneindia.com/news/world/us-slams-chinas-strategy-to-cripple-taiwans-communications-pushes-back-with-new-legislation/
[xv] Just Security. “China’s Shadow Fleet War on Taiwan’sUndersea Cables.” 2025.https://www.justsecurity.org/113221/chinas-shadow-fleet-war-on-taiwans-undersea-cables/
[xvi] Domino Theory. “Taiwan’s Internet Cable Problems RunDeep.” 2025. https://dominotheory.com/taiwans-internet-cable-problems-run-deep/
[xvii] Al Jazeera. “As undersea Cables Break Down, ProvingSabotage a Difficult Task.” March 10, 2025.https://www.aljazeera.com/news/2025/3/10/as-undersea-cables-break-down-proving-sabotage-a-difficult-task
[xviii] Tech Policy Press. “The Most Critical ResilienceQuestions of Them All: Taiwan’s Undersea Cables.” 2024.https://techpolicy.press/the-most-critical-resilience-questions-of-them-all-taiwans-undersea-cables
[xix] Domino Theory. “Taiwan’s Internet Cable Problems RunDeep.” 2025. https://dominotheory.com/taiwans-internet-cable-problems-run-deep/
[xx] U.S. Senator John Curtis. “Countering Chinese Sabotageof Taiwan’s Undersea Cables Act” [PDF]. June 2025.https://www.curtis.senate.gov/wp-content/uploads/2025/06/CAN256105.pdf
[xxi] The Guardian. “Taiwan Investigating Chinese Vesselover Damage to undersea Cable.” January 7, 2025.https://www.theguardian.com/world/2025/jan/07/taiwan-investigating-chinese-vessel-over-damage-to-undersea-cable
[xxii] Just Security. “China’s Shadow Fleet War on Taiwan’sUndersea Cables.” 2025.https://www.justsecurity.org/113221/chinas-shadow-fleet-war-on-taiwans-undersea-cables/
[xxiii] Vox. “China–Taiwan Conflict, Explained.” 2025.https://www.vox.com/world-politics/390895/china-taiwan-conflict
[xxiv] Just Security. “China’s Shadow Fleet War on Taiwan’sUndersea Cables.” 2025.https://www.justsecurity.org/113221/chinas-shadow-fleet-war-on-taiwans-undersea-cables/
[xxv] Global Taiwan Institute. “Taiwan’s DigitalVulnerabilities.” June 2025.https://globaltaiwan.org/2025/06/taiwans-digital-vulnerabilities/
[xxvi] Tech Policy Press. “The Most Critical ResilienceQuestions of Them All: Taiwan’s Undersea Cables.” 2024.https://techpolicy.press/the-most-critical-resilience-questions-of-them-all-taiwans-undersea-cables
[xxvii] The Guardian. “Risk of undersea Cable Attacks Backedby Russia, China Likely to Rise, Report Warns.” July 17, 2025.https://www.theguardian.com/technology/2025/jul/17/risk-undersea-cable-attacks-backed-russia-china-likely-rise-report-warns
[xxviii] U.S. Congress. S.2222, 119th Congress. “All Info.”https://www.congress.gov/bill/119th-congress/senate-bill/2222/all-info
[xxix] U.S. Senator John Curtis. “Curtis, Rosen IntroduceBill to Counter Chinese Sabotage of Taiwan’s Undersea Cables.” June 2025.https://www.curtis.senate.gov/press-releases/curtis-rosen-introduce-bill-to-counter-chinese-sabotage-of-taiwans-undersea-cables/
[xxx] Reuters. “US Aims to Ban Chinese Technology SubmarineCables, FT Reports.” July 16, 2025.https://www.reuters.com/world/china/us-aims-ban-chinese-technology-submarine-cables-ft-reports-2025-07-16/
[xxxi] Smart Cables. “SMART Cables Initiative.” 2025.https://www.smartcables.org/
[xxxii] Tech Policy Press. “The Most Critical ResilienceQuestions of Them All: Taiwan’s Undersea Cables.” 2024.https://techpolicy.press/the-most-critical-resilience-questions-of-them-all-taiwans-undersea-cables}