China is pressing a gray zone campaign against Taiwan beneath the waves, using civilian-looking ships to cut or threaten the fiber-optic cables that carry almost all of Taiwan’s internet and financial traffic. The effect is strategic pressure without open war. Taiwanese officials describe a deliberate pattern. Coast Guard Capt. Juan Chung-ching warned in August 2025 that such incursions “severely undermine peace and stability,” adding, “We are stepping up patrols in this area, monitoring for any vessels engaging in disruptive or destructive activities.” Taiwan’s response blends law enforcement, real-time monitoring, and constant patrols, but the tempo of incidents shows the threat is persistent and aggressive.
Incident One: Matsu’s Double Cut, February 2023
In February 2023, two Chinese vessels, described as fishing boats, severed the only two cables that connect Taiwan’s outlying Matsu islands to the main island. Both lines went down within six days, leaving about 14,000 residents with minimal internet for nearly two months. Analysts said this could not be coincidental. The twin cuts did more than inconvenience people. They revealed how fast Taiwan could mobilize repair ships, what backup links existed, and how authorities communicated under stress. That is valuable intelligence for any future crisis. The episode signaled an aggressive testing rhythm, where China could claim maritime accidents while demonstrating it can isolate a Taiwanese community at will.
Incident Two: Xingshun 39 Hits a Trans-Pacific Link, January 2025
In early January 2025, the Tanzania-flagged Xingshun 39, controlled by a Hong Kong company and crewed by Chinese nationals, disabled its tracking system near Keelung and dragged its anchor across a major cable that links Taiwan to Asia and onward to the United States. Investigators later connected the ship to alias identities and earlier registrations used to hide ownership. Industry analysts note that dragged anchors are a common cause of breaks, but the pattern here looked intentional. As Kevin Frazier explained, “The simplest way for a bad actor to break a cable is to make it look like one of the accidents that commonly cause such breaks.” Ray Powell put the gray zone logic plainly: “You just have to be just deniable enough so that even though everybody knows it’s you, they can’t prove it’s you.” The incident fit that script, and it briefly forced rerouting of data flows while Taiwan assessed damage.
Incident Three: The Thwarted Mongolia-Flagged Attempt, Mid-January 2025
Only days after the Xingshun 39 cut, Taiwan’s Coast Guard reported blocking a Mongolia-flagged ship with a Chinese name as it maneuvered near protected cable routes. Authorities cited low-speed movements inside warning zones and transponder irregularities, behaviors that match cable-cutting tradecraft seen around Taiwan. Although no cable was severed, the approach closely mirrored other cases that used flags of convenience, shell companies, and rapid name changes. Barbara Kelemen described the statistical red flags that point to malice: “If you just look at the data, like how often these incidents are now occurring and how many cables are suddenly damaged at the same time, and you include into that the proximity of some of those ships near those cables, you have statistical deviation which suggests that there is something else going on.”
Incident Four: Hongtai 58 and the Penghu Line, February 25, 2025
On February 25, 2025, the Togo-flagged Hongtai 58, with a Chinese crew and a history of frequent name and flag changes, severed the TP3 cable linking Taiwan’s main island to Penghu. Taiwan’s Coast Guard had observed the ship loitering and issued radio warnings. Track data later matched an anchor drag straight across the seabed over the cable route, which officials said is not how a ship typically moves while anchored. Prosecutors showed that electronic charts clearly marked the cable’s location. In June 2025 a Taiwan court sentenced the captain, identified as Mr. Wang, to three years in prison. The court said the damage “seriously interferes with the government and society’s operations,” calling the impact “enormous” and condemning the act. During the case, a prosecutor noted the vessel was “highly suspicious,” with only one cargo record in a year and repeated identity changes meant to hide ownership. This was a landmark conviction under Taiwan’s updated telecommunications law and a direct answer to China’s use of a shadow fleet.
The pattern ties back to China’s strategy of coercion without a formal shot. Ships linked to Chinese interests switch off AIS tracking, operate under flags of convenience, change names, and drag anchors over charted cable routes. Analysts call this civil-exploitation lawfare. It exploits legal gaps at sea to mask state-backed activity behind commercial veneers. As one Taiwanese official tally showed, cables to the Matsu islands were cut 12 times in 2023 alone, at a repair cost of NTD 96.4 million, roughly USD 2.9 million. The aggressiveness is now explicit. Chinese state entities publicly showcased a deep-sea cable-cutting capability in early 2025, with systems built to operate down to 4,000 meters. The message is that undersea infrastructure is a battlefield and Beijing intends to dominate it.
Cable breaks are frequent worldwide, so networks are built with redundancy. Even so, each cut triggers a race for specialized repair ships, stable weather, permits, and coordination with operators. That can stretch into weeks. Taiwan’s experience shows the cost adds up fast. Legal friction slows things further. Outside territorial waters, jurisdiction rests with flag states, and deliberate intent is hard to prove. Al Jazeera’s reporting showed how Europe struggled to investigate suspected Chinese and Russian shadow vessels in the Baltic when ships lingered just outside territorial limits. That same playbook complicates Taiwan’s ability to impose accountability at sea, which is exactly why gray zone sabotage is attractive to Beijing.
Taiwan’s Countermoves: From Law to 24-Hour Patrols
Taiwan has shifted from passive repair to active defense. In 2023 it amended the Telecommunications Management Act to treat deliberate cable damage as a crime and raise penalties. In 2024 it designated ten domestic submarine cables as critical infrastructure, bringing stricter protection and oversight. Technically, Taiwan is deploying the Submarine Cable Automatic Warning System that pings nearby ships not to anchor in danger zones. Operationally, Coast Guard cutters now patrol around the clock near key routes such as TP3. Dozens of radar operators watch for slow-moving vessels within one kilometer of a cable. Suspicious ships receive radio warnings, and patrol craft close to board or escort them away under the Coast Guard Act and tighter port state control rules. Reuters reported a rolling blacklist of 96 China-linked boats, many of them in poor condition and used as expendable tools. Flotilla commander Jenson Chien described several as “like cannon fodder, piles of scrap metal,” adding, “They employ minimal resources to disrupt and sever our connections.”
China frames these events as accidents, but the operational behavior and the public unveiling of cable-cutting technology point to intent. The International Cable Protection Committee estimates 150 to 200 faults occur each year worldwide. That background noise is precisely what saboteurs exploit. The repeated clustering of incidents around Taiwan, the use of alias identities, and the targeting of both domestic and international lifelines look like preparation for a larger crisis in which early strikes against communications would paralyze decision making. As Herming Chiueh, Taiwan’s deputy digital minister, warned, “Some scholars have said that World War III could begin with the cutting of undersea cables. I think that’s quite realistic.”
Taiwan’s landmark conviction in the Hongtai 58 case shows that attribution and punishment are possible, at least within territorial reach. Yet gray zone tactics thrive on legal ambiguity. That is why Taiwan is pairing prosecutions with persistent presence at sea, machine-speed alerts, and international coordination with cable operators and partners. The goal is to raise the cost of sabotage and shorten response times. As Powell observed, saboteurs keep calculating that “the response will not be bad enough.” Taiwan is working to change that calculus. Keeping the island connected is not just a technical chore. It is a front line in resisting an aggressive campaign to isolate and absorb a free society by cutting its digital arteries first.
ACZ Editor: It is nearly impossible to protect undersea cables without massive and expensive patrols and restrictions of sea traffic. China knows this is effective. Cutting off Taiwan from communications is as straightforward as cutting the cables and jamming the satellite (preventing civilian comms but not military comms).