How underwater drones are threatening to escalate South China Sea tensions

On April 15, American defence secretary Ashton Carter announced that the US is on the verge of deploying “new undersea drones in multiple sizes and diverse payloads that can, importantly, operate in shallow water where manned submersibles cannot”. He chose his visit to the US aircraft carrier Stennis, sailing in the South China Sea, to make the announcement, thus sending a clear message to China.

The initial role of the unmanned underwater vehicles is likely to be intelligence, surveillance and reconnaissance. But they could also be used to track “enemy” submarines and even launch missiles and unmanned aerial vehicles. Such drones could easily enter territorial seas and even harbours undetected. Amid tightening tensions in the South China Sea, this technological “threat” raises controversial legal and political questions surrounding their use. Indeed, the proliferation of drones and their roles create conflicts with the 1982 UN Convention on the Law of the Sea.

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These developments will clearly complicate the already strained US-China relationship regarding surveillance activities in the South China Sea. That relationship has already been sorely tested by the EP-3 (2001), the Bowditch (2001), the Impeccable (2009), the Cowpens (2013) and the Poseidon (2014) encounters. These incidents all involved Chinese challenges to US naval surveillance vessels and aircraft undertaking missions in its 200-nautical-mile exclusive economic zone that China perceived to be a threat to its security.

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China and the US have converging strategic trajectories. China is developing what the US calls an “area denial strategy” designed to control China’s “near seas” and prevent access by the US in the event of a conflict – say between China and Taiwan. The US response is the air-sea battle concept, which is intended to cripple China’s command, control, communications, computer and intelligence, surveillance and reconnaissance systems. This is the “tip of the spear” for both, and both are trying to dominate this sphere over, on and under China’s near seas. For both, drones are becoming the tip of that tip.

The US is quickly moving to the use of aerial and surface drones, as well as undersea drones for surveillance. Several countries in the region, including China, Malaysia and Thailand, do not allow military activities in their exclusive economic zones without permission. Thus, the use of drones is already creating controversy: in June 2011, Chinese jets “chased away” an unidentified US surveillance jet – rumoured to be a Global Hawk drone – over the Taiwan Strait. Despite China’s protests that such flights “severely harmed mutual trust and were a major obstacle to better military ties”, the then-chairman of the joint chiefs of staff, Admiral Michael Mullen, vowed to press ahead with such surveillance flights.

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For decades, military and civilian satellites have undertaken marine scientific research in other nations’ EEZs without the permission – or sometimes even the knowledge – required by the UN Convention on the Law of the Sea. But now there is a new array of drones.

The Seaglider is just one example. It is a small, energy-efficient unmanned underwater vessel that uses a new form of propulsion that changes the vehicle’s buoyancy and allows it to ascend and descend as a means of moving forward. These vessels have extremely low energy demands which enable both endurance and stealth due to the absence of noise-producing engines. This makes them ideal for surveillance missions.

These advances will generate legal and political problems. International law, including the UN convention, prohibits overflight of foreign 12-nautical-mile territorial seas without permission. And in a foreign territorial sea, submarines – manned or unmanned – must surface and show their flag. In the 200-nautical-mile EEZ, the foreign user cannot conduct scientific research without permission.

Surface and underwater drones may well be regarded by some as marine scientific research “equipment”. Some countries like China claim that surveying for military purposes is a “preparation of the battlefield” and thus “non-peaceful” and not allowed.

Given these legal and strategic differences, the proliferation of drones is bound to become more politically fraught as the scale and scope of intelligence collection activities expand, involving levels of activity unprecedented in peacetime. Being more intrusive, they will generate tensions and more frequent crises, leading to less stability in affected regions like the East and South China seas.

China is trying to catch up and has made dramatic progress. Advances are most evident in aerial drones, but it is also accelerating its development of underwater and surface drones. This effort is at least partially attributable to their utility in maritime territorial disputes.

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China’s use of drones in the East China Sea has already raised political hackles. In response to China’s intended deployment of an aerial drone, Japanese defence minister Itsunori Onodera announced that Tokyo would “consider shooting down drones that enter Japanese airspace”, significantly raising the prospects of escalation. Soon after, Prime Minister Shinzo Abe approved a plan for the Self-Defence Forces to “engage drones intruding into the country’s airspace”. In response to Abe’s remarks, the Chinese Ministry of National Defence spokesperson stated that shooting down a Chinese drone would constitute an “act of war”.

What to do? The default option is to “do nothing” – just let the rules evolve. But doing nothing means that where the text of a governing treaty leaves matters ambiguous or unresolved, the practice of states will become particularly important in determining the interpretation of the treaty’s provisions. The increasing use of drones may even trigger a “Grotian moment”, in which rapid, radical changes in technology accelerate the formation of customary international law.

If many coastal states enact unilateral national legislation prohibiting certain military and intelligence-gathering activities by drones in and above their jurisdictional zones, then the banning of such missions could become part of customary international law through state practice, despite the opposition of a few countries.

The US and China could try to get ahead of the curve and negotiate voluntary guidelines for the use of drones in waters under foreign jurisdiction. But, of course, realists will argue that the US should maintain its technological advantage and therefore not agree to any constraints. Thus, it is likely that more international incidents will have to be endured in order to show the necessity of doing so.

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