Cut One Line, Lose the Network for 50 Days: Taiwan's Invisible Information Lifeline

Why does this "invisible line" — the undersea cable — deserve to be treated as a national-security matter on par with missiles and warships? Because it is one of the options China has for dealing Taiwan a severe blow without "firing the first shot."

Imagine a gray-zone script: at some moment of heightened tension, several of the main international cables around Taiwan "fail" in quick succession within a short window. In an instant, Taiwan's outbound financial transactions, cloud services, and cross-border communications are badly disrupted; stock and currency markets may panic, businesses may grind to a halt, and the international community may find itself briefly "unable to reach Taiwan." Throughout it all, there are no missiles, no landings — yet Beijing can publicly claim "this was just a string of maritime accidents," making it hard for the international community to assign blame, let alone respond. This is exactly what makes a cable attack so insidious: it can produce the effect of a near-blockade while hiding itself in the fog of "accident."

Precisely because of this, undersea-cable resilience is not a minor matter for some technical department — it is a cornerstone of Taiwan's overall defense. What it protects is not just the internet, but Taiwan's ability, in a moment of crisis, to "stay connected to the world and not be easily isolated."

Those who favor the "accident theory" will say: undersea cables fail hundreds of times a year worldwide, most from fishing trawls or dragged anchors by accident, and over-accusing is hard to prove and risks falling into cognitive warfare itself. This baseline is correct and must be honestly acknowledged.

But several incidents from 2025 into 2026 are hard to dismiss as "pure accident":

• In January 2025, a Tanzanian-flagged ship controlled by a Hong Kong company and crewed by Chinese nationals switched off its tracking system, then dragged its anchor and severed a critical cable connecting Taiwan, Asia, and the United States ^[1].
• In February 2025, the "Hong Tai 58," crewed by Chinese nationals, damaged a cable connecting Penghu to Taiwan's main island; Taiwan detained the vessel ^[6].
• In April 2026, Matsu's Taiwan-Matsu No. 3 cable was cut again, this time suspected to involve a Chinese salvage barge ^[3].
• And China's own state-owned China Ship Scientific Research Center publicly disclosed, in early 2025, a device capable of cutting cables at a depth of 4,000 meters ^[1].

"Turning off the tracker, operating repeatedly in the same waters, carried out by specific vessel registries" — combined with the other side openly disclosing its own cable-cutting capability — this is already hard to dismiss entirely as fishing-boat accidents.

This calls for a level-headed method: separate the "individual case" from the "pattern."

Any single cable-cutting incident is often hard to prove as intentional — flag states fail to act, evidence gathering on the seabed is difficult, and most individual cases end up going nowhere. This is precisely the calculation behind China's "shadow fleet": achieving disruption at minimal risk and maximum ambiguity ^[1]. So for each individual case, we should honestly label it "unproven."

But look at dozens of these incidents together, and a pattern emerges: repetition, specific vessel registries, deliberately switching off tracking, and the other side openly disclosing a cable-cutting vessel — this adds up to a reasonable reading of "battlefield pre-positioning" (confidence: medium): Beijing, incident by incident, is eroding Taiwan's resilience while pre-positioning itself for a potential conflict ^[2]. This is also exactly the "salami-slicing" logic described in our gray-zone report — each individual slice looks like an accident, but added together they form a methodical war of attrition. The individual case is fog; the pattern is signal.

Here we need to add a dimension that has often been overlooked in the past, yet matters more and more: a cable cut is often accompanied by a cognitive-warfare campaign.

Whenever a cable incident happens, sensational claims quickly surface on social media — "Taiwan's international undersea cables have been cut down to almost nothing," "Taiwan is about to become a digital island cut off from the internet." Taiwan's FactCheck Center has debunked this kind of rumor before: in reality, Taiwan has about 15 international undersea cables, and in one particular episode only 4 were reported as disrupted — nowhere close to "all gone dark" ^[9].

The purpose of this tactic is clear: use the panic of "information infrastructure collapse" to amplify the psychological impact of a single technical incident, and shake the public's confidence in the nation's resilience. So for Taiwan, undersea-cable resilience actually has two layers: one is "physical" — can a cut line be repaired, can traffic be rerouted; the other is "psychological" — when a line is cut, does society get swept into chaos by rumor along with it. Only when both layers hold is this true resilience.

Precisely because individual cases are hard to attribute, what Taiwan most needs to do is actually clear: stop getting stuck on "was this China's doing," and first build out "even if it's cut, the line stays up." And in recent years, this work has genuinely been progressing.

The most representative example is the multi-layer resilience network Chunghwa Telecom has built, called "Sea, Land, and Sky": it integrates undersea cables, mobile and fixed networks, microwave links, and satellites so that they back each other up — the undersea cable is the backbone, fiber, mobile, and microwave support the network within the islands, and satellites serve as the last line of defense in extreme scenarios ^[8]. When Matsu's cable was cut in April 2026, avoiding a repeat of the 50-day nightmare came down to the microwave backup that kicked in immediately (microwave backup coverage for outlying islands now exceeds 100%).

Looking further ahead, there is LEO satellite service. The LEO satellite service that Chunghwa Telecom operates in partnership with Eutelsat OneWeb entered commercial promotion in 2026 — this is the embryo of Taiwan's own version of "Starlink," so that when cables are cut entirely, satellites overhead can still carry basic communications ^[7]. On the hardware side, the new "Taiwan-Matsu No. 4" cable is expected to be completed in June 2026, along with an additional Taiwan-Penghu-Kinmen cable, spreading out the routing for both international and outlying-island connections; on the institutional side, the legislative amendments known as the "Seven Undersea Cable Acts" have already passed their first reading, aiming to make sabotage of critical undersea cables a criminal offense and raise penalties ^[7].

Of course, gaps remain. During Matsu's 50-day outage in 2023, one pain point was slow deployment of repair vessels — Taiwan's own capacity for laying and repairing cables is still insufficient, and if multiple cables were damaged at once, the risk of queuing up for repairs would remain. More advanced approaches such as SMART cables (which build in sensors that can give early warning and quickly pinpoint faults) are also still only at the advocacy stage ^[5].

The gaps that still need filling also include who bears the "money" and the "responsibility." Cables are mostly owned and maintained by telecom operators, yet their resilience is a matter of national security. When market incentives (commercially, an extra layer of backup is just an extra cost) diverge from national-security needs (strategically, backup is a necessity), the government has to step in — using subsidies, regulation, or public-private cooperation to make sure that backup investments, which look wasteful in peacetime but could be lifesaving in wartime, are not skipped simply because they don't pay off in the short term. Resilience has never been free; but compared with the cost of a 50-day outage, it is far cheaper.

Cable fragility is not a worry unique to Taiwan. Since 2023, the Baltic Sea has also seen a string of cable and undersea pipeline sabotage incidents involving "dragged anchors," prompting NATO to launch its "Baltic Sentry" operation, deploying ships and air patrols to strengthen protection. Europe's experience offers Taiwan two lessons: first, "switch off tracking, sabotage by dragging anchor, hard to attribute" is a gray-zone script being used repeatedly, and what Taiwan faces is not an isolated case but a new kind of global coercion; second, the response has to be "collective" — through intelligence-sharing among allies, joint patrols, and coordinated pressure on flag states, turning a cost that a single country cannot pursue on its own into a cost the international community imposes together.

For Taiwan, this means undersea-cable defense is also a "diplomatic" issue: laying out the "pattern" of each cable cut for the international community to see, and sharing surveillance intelligence with like-minded countries, can both raise deterrence and, if something really does happen, put the world in a position to speak up for Taiwan.

Pulling all of this together, Taiwan's plan for undersea-cable resilience does not actually need to wait for a court to rule on "was this China's doing" before acting:

• Deterrence and enforcement: Strengthen patrols around undersea cables, amend the law to make sabotage of critical infrastructure a criminal offense (the "Seven Undersea Cable Acts"), and detain and prosecute vessels involved ^[6].
• Backup: Microwave, satellite, and LEO satellites (Taiwan's own version of Starlink) as communications fallbacks when a cable is cut, so that "one cable down" does not mean "the whole network down" ^[7][8].
• Detection: Deploy SMART cables with built-in sensors, giving early warning before a cut and rapid localization after one ^[5].
• Structure: Diversify landing stations and expand domestic cable-laying and repair-vessel capacity.
• Internationalization: Make the "pattern" public and work with allies to press flag states for accountability — exactly the same move Manila used to throw the cost back onto Beijing over Scarborough Shoal.

Don't assume undersea cables are only a matter for governments or big corporations. When Matsu went offline for 50 days, the people who really suffered were local small businesses — unable to process card payments, unable to receive online orders, children unable to attend remote classes, the elderly unable to register for medical appointments. In an age when digital payments, cloud services, and telemedicine have already woven themselves deep into daily life, "going offline" is not an inconvenience — it is an entire life grinding to a halt. Undersea-cable resilience, at bottom, protects every ordinary person's right to "get on with a normal life" — which is exactly why it should not be an issue that only national-security experts talk about, but something everyone who lives their life through the internet should keep in mind.

The state: Govern undersea cables as national-security-grade critical infrastructure — patrols plus criminalization plus backup plus diversified landing stations plus a self-sufficient repair-vessel fleet plus international accountability, while making the sabotage "pattern" public. At the same time, build the "cognitive warfare that follows a cable cut" into the response playbook, using authoritative information to suppress panic-driven rumors from the very first moment.

Industry (telecom / data centers / cloud): A cable cut disrupts international connectivity and cloud services, hitting finance and cross-border e-commerce first. Build multi-path routing and satellite backup, and regularly drill for "cable cut" scenarios — treat "the cable might get cut" as a basic operating assumption, not a low-probability accident.

SMEs: SMEs that depend on the cloud and cross-border payment flows need "offline backup" and contingency plans; when facing the "panic-driven information warfare that follows a cable cut," media literacy is also part of resilience — don't let a single technical incident be amplified by rumor into a collapse of your confidence in Taiwan.

The threats Taiwan spends the most effort guarding against are missiles in the sky and warships at sea; but what is most likely to leave the world "unable to hear Taiwan" first is those few silent lines on the seabed. The good news is that, from Sea, Land, and Sky to LEO satellites, from Taiwan-Matsu No. 4 to the Seven Undersea Cable Acts, Taiwan is weaving this lifeline denser and more resilient. True security is not betting that it will never be cut — it is making sure that even after it is cut, Taiwan is still online, and still not thrown into chaos by rumor. Whether the missiles come is not something Taiwan can decide; but whether Taiwan can keep functioning normally, and keep speaking to the world, after those lines on the seabed are cut — that is something Taiwan can, and must, start preparing for now, one line and one layer at a time.