Indonesia, explained.
Photos of the object released by police in Lombok (Handout)
A torpedo-like object found off Lombok may not qualify as a “ship”, challenging categories that weren’t designed for unmanned vessels.
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No flag, no crew, no rights – what Indonesia can legally do about the Lombok droneNo flag, no crew, no rights – what Indonesia can legally do about the Lombok drone
Indonesian fishers found a torpedo-like object in the waters north of Gili Trawangan, Lombok, on 6 April. The exact coordinates of the discovery and the object’s direction of travel are unknown. Much else remains speculative: whether it was moving within Indonesia’s archipelagic sea lane (ALKI II) in the Lombok Strait or outside it, what activity it was conducting, and whether the object is attributable to a state.
Speculation persists that the object is an unmanned underwater drone linked to a Chinese company. The investigation continues.
Under international law, all ships enjoy the right of innocent passage through Indonesian territorial and archipelagic waters, and the right of archipelagic sea lanes passage (ASLP) through routes normally used for international navigation in Indonesian archipelagic waters and the adjacent territorial sea (whether designated or not).
But those rights belong only to a ship. This raises the threshold question: does the object found off Lombok qualify as a “ship” under international law, and is it therefore entitled to any navigation rights through Indonesian waters at all?
The United Nations Convention on the Law of the Sea (UNCLOS) never defines “ship”, but the rules it prescribes reveal the drafters’ assumptions. The innocent passage regime, for instance, requires a vessel to navigate on the surface, fly its flag, observe international collision regulations, comply with coastal state laws, and follow designated sea lanes and traffic separation schemes. All of these presuppose a vessel that is visible, identifiable, and capable of following passage rules and communicating with external parties.
The object found off Lombok likely fails on every count. According to media reports, it bears some Chinese characters meaning “research and development” and the logo “CSIC”, which is associated with China Shipbuilding Industry Corporation, but no flag is visible. There is no indication it can surface on command, identify itself, follow passage rules, or respond to Indonesian authorities. If the object is not a ship, Indonesia may intercept and confiscate it. However, this would put Indonesia at odds with major powers that recognise unmanned underwater vehicles as ships.
The real threat for Indonesia may be far less visible: small, undetectable drones quietly collecting data across Indonesian waters with no flag, no crew, and no one to call.
Even if the object qualifies as a ship, what it was doing remains unknown. That matters because passage loses its innocent character if the vessel conducts “research” or “survey,” or anything else “not having a direct bearing on passage”. The same prohibition applies to ASLP. A vessel transiting through the Lombok Strait, which falls under Indonesia’s ALKI II, may not conduct any research or survey without Indonesia’s prior authorisation. Either way, the object’s equipment points squarely toward exactly that kind of activity. It was reportedly fitted with underwater sensors, sonar, and oceanographic cables, and found to contain an acoustic Doppler current profiler. Police described it as bearing “characteristics commonly found in underwater observation or survey equipment”.
What Indonesia can do against a ship conducting “research” or “survey” in its waters depends on two questions: whether the ship was exercising innocent passage or ASLP, and whether it is sovereign immune. That second question also turns on the nature and purpose of the ship’s activity.
On the first question, it is unclear which passage regime applies. If the ship was exercising innocent passage, Indonesia may take whatever steps necessary to stop it, including physical removal. ASLP is more restrictive as UNCLOS does not explicitly empower the coastal state to take enforcement action even where prohibited activities are underway.
On the second question, it is unclear whether the ship qualifies as sovereign immune. If it does, Indonesia cannot take enforcement action against it. Sovereign immune vessels generally include warships and other government ships operated for non-commercial purposes. An unmanned vessel likely cannot qualify as a warship because a plain reading of UNCLOS requires a commissioned officer in command and military personnel aboard. But it may still qualify as a government vessel operated for non-commercial purposes, particularly if it was “chartered by states either for a given time or by the voyage” provided it was “exclusively used on governmental and non-commercial service”. If Indonesia accepts that characterisation, its options narrow to demanding the vessel leave its waters (or, given that it is unmanned, returning it to the flag state) and holding that flag state responsible for any loss or damage.
Whether the object falls into that category remains unclear and may be one of the matters the investigation will reveal. The CSIC markings suggest a private vessel, but ownership by a state-owned enterprise complicates attribution, especially since data collected through “research” or “survey” is inherently dual-use, serving pure science, commercial use, and military planning simultaneously. Difficult as that determination is in practice, it defines the ceiling of permissible action by Indonesia.
The incident off Lombok points to something larger. Indonesia is an archipelagic state with vast sovereign waters and multiple strategic chokepoints, and the object found by fishers may be far from unique. While nuclear-powered submarines transiting through those chokepoints tend to dominate the security conversation, the real threat for Indonesia may be far less visible: small, undetectable drones quietly collecting data across Indonesian waters with no flag, no crew, and no one to call.
About the author
Dita Liliansa
Dita Liliansa is a Research Fellow at the Ocean Law and Policy Programme of the Centre for International Law (CIL), National University of Singapore (NUS).
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