🛰️ Taiwan Gray Zone & Submarine Cable Monitor

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Who Can Board and Enforce?

Law of the Sea 03 • Hot Pursuit • Right of Visit • Universal Jurisdiction

In short

When a foreign ship cuts a cable off Taiwan, can the Coast Guard board it? The answer lies in a few "enforcement jurisdiction" tools: the right of visit (UNCLOS Art. 110), hot pursuit (Art. 111), coastal-state protective powers, and domestically the Telecommunications Management Act Art. 72 and the Coast Guard Act. The trouble is that each tool has strict thresholds — the right of visit's listed grounds do not include cable damage, hot pursuit must be uninterrupted, and domestic law is constrained by flag-state jurisdiction. To fill the gap, some scholars propose extending universal jurisdiction to malicious cable-cutting by analogy to piracy — still a developing proposal.

SERIES → Maritime Rights Int'l Law Enforcement TW Cables Global Cables
On the radar, the ship is still there. It has just dragged a cable apart and is heading out to sea at 8 knots. The patrol boat is not far off, engines already running.

The commander needs only one order — but he knows that before he gives it, he must run a full international-law checklist in his head: which zone is it in? What flag does it fly? Do I have the right to board? This article is that checklist.

From "Is There a Law" to "Can I Act"

The previous article showed that international law gives cables "prescriptive" protection but withholds the key to "enforcement." This article asks the enforcement side: under what conditions may a state actually act against a foreign ship — board, intercept, seize, prosecute?

Beneath the grand principle of high-seas freedom, UNCLOS leaves a few narrow doors. They are the rare moments a coastal state may reach out — but each door has a strict lock.

The Toolbox: Four Keys and Their Locks

UNCLOS Art. 110 · Right of Visit
A warship's high-seas power to inspect
A warship may visit and inspect a foreign ship reasonably suspected of piracy, the slave trade, unauthorized broadcasting, or being stateless / falsely flagged (demand papers, board if needed).

The lock: the listed grounds do not include "submarine cable damage." Unless a cable-cutting ship also triggers one of the above, Art. 110 cannot be invoked on cable-damage grounds alone.
UNCLOS Art. 111 · Hot Pursuit
Chasing from your waters all the way to the high seas
When a foreign ship breaches a coastal state's laws in internal waters, the territorial sea, the contiguous zone, or the EEZ, the coastal state may pursue it without interruption from that zone out onto the high seas and intercept it.

The lock: the pursuit must be "uninterrupted" and ends the moment the chased ship enters its own or a third state's territorial sea — often too slow for an elusive cable-cutter noticed only after the fact.
UNCLOS Arts. 25 / 220 · Coastal-State Protective Powers
Protection and environmental jurisdiction in the territorial sea
A coastal state may take steps in its territorial sea to prevent passage that is not innocent (Art. 25), and exercise graduated enforcement over vessel pollution in the EEZ (Art. 220).

The lock: these hinge on "innocent passage" and "pollution," and struggle to cover deliberate cable damage in distant waters.
Telecommunications Management Act §72/§72-1 · Coast Guard Act §4/§5
Taiwan's domestic tools
Art. 72 of the Telecommunications Management Act (2023 amendment) criminalizes intentional cable damage; Coast Guard Act Arts. 4-5 grant enforcement, boarding, and investigation powers in waters under jurisdiction.

The lock: reach is mainly Taiwan's territorial sea and EEZ; against high-seas foreign ships it remains constrained by exclusive flag-state jurisdiction, making extraterritorial application hard.

Why Do These Tools So Often "Not Apply"?

Put the four keys back into real cases — Xing Shun 39 in January 2025, Hong Tai in February — and you see why they keep jamming.

🔴 Timing: noticed only after the fact
Cable cuts often happen in deep water, at night, with AIS off. By the time the carrier detects the outage and the Coast Guard reaches the scene, the ship has sailed. Hot pursuit demands "uninterrupted" chase, but enforcers miss even its starting point.
🔴 Grounds: cable damage is not on the visit list
Art. 110's listed grounds for visit do not include "cable damage." Even if the ship is caught, the basis for boarding on the high seas stays weak unless it also triggers piracy or another listed ground.
🔴 Flag: flag of convenience + shell company
The ship flies a flag of convenience such as Tanzania, is held by a Hong Kong shell company, and the real owner hides in layers. Even with domestic law, Taiwan hits the wall of exclusive high-seas flag-state jurisdiction, and prosecution depends on the flag state's cooperation.

By contrast, the Baltic experience — cases like Yi Peng 3 and Eagle S — shows some coastal states boarding and even detaining suspicious vessels suspected of dragging anchors across cables, a will to do more than protest. The International Advisory Body for Submarine Cable Resilience, established in 2024, tries to weave scattered national actions into cross-border cooperation. Constrained by its diplomatic status, Taiwan can still draw lessons from this.

A Proposal: Treat "Malicious Cable-Cutting" Like Piracy, Under Universal Jurisdiction?

Faced with the enforcement gap left by flag-state jurisdiction, some scholars propose a bold direction: fold deliberate damage to submarine cables into universal jurisdiction, by analogy to piracy.

Why Piracy?In international law, pirates are hostis humani generis — enemies of all humankind. Any state may board, arrest, and prosecute them on the high seas, free of flag-state limits, because piracy harms the shared interest of all seafaring nations.

The advocates' analogy: submarine cables are globally shared critical infrastructure, and deliberate cutting likewise harms a transnational public interest, often tied to gray-zone coercion. If folded into universal jurisdiction like piracy, any state could board and prosecute — precisely filling the crack left by exclusive flag-state jurisdiction. The "peaceful uses of the high seas" principle in UNCLOS Arts. 88 and 301 could serve as a normative anchor.

A practical caveat: this remains a developing scholarly proposal, not positive international law. "Upgrading" malicious cable-cutting to a universal-jurisdiction offense would need new treaty consensus or sustained state practice, unlikely in the short term. Until then, continuous maritime awareness, cross-border evidence chains, and public pressure remain the most practical path for a diplomatically constrained Taiwan — and the very reason this site publishes suspicious AIS tracks.

FAQ

What is the right of visit?
The right of visit (UNCLOS Art. 110) lets a warship inspect a foreign ship on the high seas, but only in specific cases: reasonable suspicion of piracy, the slave trade, unauthorized broadcasting, or that the ship is stateless or falsely flagged (e.g. actually of the warship's nationality). Inspection usually means demanding the ship's papers and, if needed, boarding. Unfortunately "submarine cable damage" is not among Art. 110's listed grounds — a major limit on cable enforcement.
What is hot pursuit?
Hot pursuit (UNCLOS Art. 111) lets a coastal state, when it has good reason to believe a foreign ship has broken its laws in internal waters, the territorial sea, the contiguous zone, or the EEZ, pursue that ship from those waters in an uninterrupted chase onto the high seas and intercept it. But the pursuit must be "uninterrupted" and ends once the ship enters its own or a third state's territorial sea — in practice a poor fit for an elusive cable-cutter.
Can Telecommunications Management Act Art. 72 be enforced against foreign ships?
Art. 72 (2023 amendment) criminalizes intentional cable damage and is Taiwan's domestic basis against cable cuts. But its reach is mainly Taiwan's territorial sea and EEZ; against foreign ships operating on the high seas or in other states' waters it remains constrained by exclusive flag-state jurisdiction, creating an extraterritorial-application problem. Coast Guard Act Arts. 4-5 grant enforcement and inspection powers within waters under Taiwan's jurisdiction.
Why do some argue for extending universal jurisdiction to cables?
Universal jurisdiction currently applies mainly to "enemies of all humankind" such as piracy and the slave trade, which any state may prosecute. Because submarine cables are globally shared critical infrastructure and deliberate damage harms a transnational public interest, some scholars propose folding malicious cable-cutting into universal jurisdiction by analogy to piracy, so any state could board and prosecute and fill the gap left by flag-state jurisdiction. This is still a developing proposal, not yet positive international law.
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Sources

The concepts on this page can be verified against these public, authoritative sources:

The enforcement tools and universal-jurisdiction proposal draw on Li Yefei, "The Legal Structure of the Ocean Basic Act, Lecture 12: Maritime Rights," Contemporary Law Journal, March 2025; Baltic cases are from public news reporting.

This page is for research and education; detection signals are leads to investigate, not legal or factual findings. See the methodology.

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