The Nonexistent Legal Basis for China’s Seizure of the U.S. Navy’s Drone in the South China Sea

In many disputes arising out of the South China Sea, China and the U.S. have different good-faith interpretations of international law. But China’s seizure of a U.S. Navy unmanned underwater vehicle (UUV) yesterday is different. Unless there are new facts to be disclosed (and I will update when China issues an official response), there is simply no plausible international legal basis for China’s action.

According to the U.S. Defense Department, the USNS Bowditch was conducting routine operations about 50 nautical miles northwest of Subic Bay in the Philippines. This would place the UUV outside of the Philippines’ territorial waters but within the Philippines’ Exclusive Economic Zone (EEZ). Ordinarily, this would mean that China has no valid jurisdiction. But because the Bowditch was also operating within 200 nautical miles of the disputed Scarborough Shoal, China might claim that the Bowditch and the UUV were actually operating inside China’s EEZ. This would be a very weak claim because the recent UNCLOS arbitral tribunal award found that the Scarborough Shoal is a rock that entitles its sovereign to only a 12 nautical mile territorial sea.

But even if one ignores the arbitral award and accepts that the UUV was inside of China’s theoretical Scarborough Shoal-based EEZ, there is still no legal basis for China to seize it. The U.S. (like most countries) believes naval ships can conduct any kind of operations in EEZs, and it is certainly true that the plain text of the UN Convention of the Law of Sea supports this view. But China has long taken the position that it has the right to restrict foreign military activities and surveillance within its EEZ. This was the basis for China’s famous (or infamous) action in taking down a U.S. EP-3 surveillance plane back in 2001 and has long been a point of dispute between the two countries.

But even if one accepted that China has the right to exclude military surveillance vessels from its EEZ, there is no justification for seizing a UUV not engaging in military surveillance. And it is highly doubtful that the UUV was conducting any kind of military surveillance since the UUV’s sole function is to gather oceanographic data for military purposes. It is not a weapons system and has no military capabilities that we know of. If military surveillance were suspected, the proper action should be to issue a warning to the U.S. vessel (which was within easy hail) and demand it cease its surveillance or leave China’s EEZ. But China didn’t do this either.

This leads me to the overarching problem with any Chinese legal justification for its actions. Under UNCLOS Article 32, “warships and other government ships operated for non-commercial purposes” retain their immunities under customary international law. This absolute sovereign immunity from seizure would be applicable even within China’s territorial waters. It certainly exists within China’s theoretical and sketchy Scarborough Shoal-based EEZ and would apply even if the UUV was conducting military surveillance.

In sum, China has seized a vessel belonging to a foreign government in clear violation of any possible theory of international law it could offer. Even if one accepts China’s expansive claims to an EEZ 50 miles off the coast of the Philippines (in violation of the arbitral award), and one accepts China’s rights to stop military surveillance (in violation of the plain text of UNCLOS), there is no way any country can accept China’s right to seize foreign naval vessels in violation of the basic principle of sovereign immunity. China has no legal basis for its action, and the U.S. should do its best to make sure other nations realize this.

The lack of legality is important because it shows that China is veering further away from a putative rules-based global order. If China tries to stay within its own interpretation of international law, at least there is a common language for debate and engagement. If China doesn’t even bother to come up with a plausible legal justification for its actions, then that is a yet another reason to worry about the stability and future of U.S.-China relations.