Taiwan Maritime Gray-Zone Glossary (Bilingual)

In short

A bilingual (English / Traditional Chinese) glossary of the terms used in Taiwan maritime gray-zone monitoring — gray-zone operations, dark vessels, AIS spoofing, MMSI, ship-to-ship transfers, SAR, flags of convenience, territorial baselines, and more. Every term has an anchor link for direct citation.

Gray Zone & Suspicious Behavior

Gray zone operations

Coercive or provocative actions deliberately kept below the threshold of open armed conflict, exploiting ambiguity and deniability. → learn more

Going dark

Deliberately switching off a vessel's AIS transponder so it disappears from conventional tracking platforms.

Dark vessel

A vessel detected by SAR satellite radar that has no matching AIS broadcast — present on the water but invisible to AIS trackers. → learn more

Loitering

Lingering at low speed within a small area, e.g. near a submarine cable — a behavior the threat score weights heavily.

Ship-to-ship transfer (STS)

Two vessels lying alongside at sea to move cargo, fuel, or catch without entering port; lawful in many cases, but also used to conceal cargo origin. → learn more

Rendezvous

A prearranged meeting of two vessels at a point at sea, often the precursor to a ship-to-ship transfer.

Shadow fleet

Aging, opaquely-owned tankers used to move sanctioned cargo (e.g. oil) while obscuring ownership and origin.

IUU fishing

Illegal, Unreported, and Unregulated fishing — fishing that breaks rules, goes unreported, or occurs outside any management regime.

Detection Technology

AIS

Automatic Identification System: a VHF radio transponder that broadcasts a ship's identity, position, speed, and course every few seconds. → learn more

AIS spoofing

Broadcasting false AIS data — fake position, speed, or another ship's identity — to conceal a vessel's true movements. → learn more

SAR (Synthetic Aperture Radar)

An active radar satellite that images metal objects on the sea surface regardless of cloud, weather, or daylight.

MMSI

Maritime Mobile Service Identity: a 9-digit number identifying a vessel; the first three digits (MID) indicate its flag state.

IMO number

A permanent 7-digit hull identifier that, unlike name or MMSI, is meant never to change over a ship's lifetime.

MID

Maritime Identification Digits: the first three digits of an MMSI, encoding the vessel's flag state.

Identity & Registration

Flag state

The country under whose laws a vessel is registered and whose flag it flies; responsible for its regulation.

Flag of convenience (FOC)

Registering a ship in a foreign open-registry state to reduce cost or oversight; over-represented among suspicious vessels.

Identity manipulation

Frequently changing a vessel's name, MMSI, or falsely reporting its IMO number to break the link to its tracking history. → learn more

Maritime Law & Geography

Territorial baseline

The line (usually the low-water coastline) from which a state's maritime zones — territorial sea, contiguous zone, EEZ — are measured.

Territorial sea (12 nm)

The belt of sea up to 12 nautical miles from the baseline, over which the coastal state has sovereignty.

Contiguous zone (24 nm)

Up to 24 nm from the baseline, where a state may enforce customs, immigration, sanitary, and fiscal laws.

Exclusive Economic Zone (EEZ)

Up to 200 nm from the baseline, where the coastal state has sovereign rights over natural resources.

Submarine cable

Undersea fibre-optic cables carrying internet and communications; Taiwan depends on them for over 95% of external connectivity. → learn more

Sources

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

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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Gray-Zone Glossary