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South China Sea: why drones are best kept out of freedom of navigation operations

July 12, 2021 GMT

US Fonops in the South China Sea are arguably already a violation of international law because they can be perceived as a threat to use force against what China considers its sovereignty and territorial integrity. They increase the risk of confrontation and conflict and are thus unwelcome by Southeast Asian states.

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Moreover, they are legally unnecessary because diplomatic protests would suffice to register the US position. Most important, they are ineffective as they have not changed China’s policies or stopped actions the US declares unlawful.

The US Navy commander argues that a shift to unmanned Fonops would provide “substantial cost savings, a reduced risk to human life, increased flexibility in escalation dynamics, and an asymmetric answer to geographically advantaged peer competitors in distant oceans”. But there are reasons that the use of drones for this purpose would increase the risk of kinetic conflict.


The normal use of drones is for intelligence, surveillance and reconnaissance missions, which are being enhanced and expanded. Indeed, this use of drones is already outpacing relevant laws and regulations.

Many new platforms are designed to operate stealthily in foreign exclusive economic zones, archipelagic waters and even territorial seas. In doing so, they may be violating the UN Convention on the Law of the Sea (Unclos), which prohibits collection of information in such waters without authorisation.

A drone undertaking a Fonop could easily be perceived to be on an intelligence mission against the target country. More important, drones ” unlike manned vessels ” may not have sovereign immunity. This makes them an inviting target for capture or destruction.

Some argue that drones are US vessels “operating legitimately at sea” and therefore enjoy sovereign immune status. According to Article 32 of Unclos, a military platform has sovereign immunity if it is a warship or a government ship operated for non-commercial purposes. But it is not clear that this applies to drones.

The terms “vessel” or “ship” are not defined in Unclos. The proponents of sovereign immunity for drones argue that a variety of treaties define “vessel” sufficiently broadly to include “autonomous and even expendable marine instruments and devices”.

But a major treaty governing interaction of ships on the high seas, the International Regulations for Preventing Collisions at Sea, defines “vessel” as “every description of water craft ... used or capable of being used as a means of transportation on water”. Even the US Congress definition of “vessel” uses the qualifier “as a means of transportation on water”.


A drone is obviously not used as a means of transportation on water. Moreover, it is not a “warship” because according to Unclos Article 29, it has to be “manned by a crew”. One could stretch the plain meaning of this definition to argue that it is “remotely” manned ” but not if it is operating autonomously. In any case, this is a reach.

The US navy commander argues that the lack of threat to human life using drones would make the intrusion less threatening and thus reduce risk of conflict. But precisely because it is unmanned, a country that perceives that its claims and laws are being violated by the drone might be more tempted to physically capture or destroy it. They might also be tempted to capture the device to gain access to its technology.

The target country may have other reasons to do so. According to Unclos Article 30, if any warship does not comply with the laws and regulations of the coastal state concerning passage through the territorial sea and disregards any request for compliance therewith which is made to it, the coastal state may require it to leave the territorial sea immediately. Since it cannot communicate with a drone directly, it may decide to capture or destroy it.

Moreover, because the activities and capabilities of drones are harder to determine remotely than those of larger manned vessels and aircraft, they may be suspected of violating the regime of innocent passage in a country’s claimed territorial sea. To determine if the drone has violated innocent passage or any other provisions of Unclos, the target state may decide to capture and examine it.

But the real purpose of transitioning to the use of drones for Fonops may be to unilaterally establish the legal rules governing their use. As the US Navy commander says, “Using unmanned systems for Fonops could help to establish the desired US government precedent regarding these platforms and the law of the sea” by communicating “expected norms regarding their usage under existing conventions and customary law”.

But precisely because the law is unsettled and controversial, a target nation may try to establish its interpretation of the rules, leading to a clash of visions and probable legal and physical conflict.

Transitioning to the use of drones for Fonops is likely to exacerbate the risk of kinetic conflict ” not diminish it.

Mark J. Valencia is an adjunct senior scholar at the National Institute for South China Sea Studies, Haikou, China

This article originally appeared on the South China Morning Post (SCMP), the leading news media reporting on China and Asia. For more SCMP stories, please download our mobile app, follow us on Twitter, and like us on Facebook.

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