The eagerly-anticipated freedom of navigation operation (FONOP) by the United States Navy (USN) in the South China Sea was initially viewed as a strong demonstration of the United States’ resolve that the waters surrounding China’s artificial islands and claimed reefs are high seas. China’s attempt to establish a de facto12 nautical mile territorial sea around these features is, as most readers of CIMSEC will know, in direct contravention of the United Nations Convention on the Law of the Sea (UNCLOS). UNCLOS clearly specifies that man-made islands and underwater features like reefs are not eligible for the 12 nm zone granted to more robust geographic features, such as rocks or naturally-formed islands capable of sustaining human habitation or economic life; the latter of these are also eligible for the prized 200 nm Exclusive Economic Zone.
Acknowledging implicitly that their features are not legally entitled to any kind of territorial sea, the Chinese instead have attempted to establish a normative regime aiming to make other actors treat the waters surrounding their features as though it were a territorial sea. Under customary international law, consistent behavior toward a particular issue can result in the practice becoming legally binding, either through generally agreed norms of behavior or a gradual solidification it into written law. Thus, for countries wishing to prevent the high seas around the Chinese features from becoming a territorial reality, it is crucial for interested parties to halt the norm-creation process before it can gather steam.
To do this, the USN thus carried out its first FONOP, sending the Arleigh Burke-class destroyer USS Lassen within 12 nm of the Chinese build-up on Subi Reef. However, simply sailing within 12 nm is not sufficient to demonstrate American resolve that the waters are high seas.
Rather, the Lassen had to have behaved within those 12 nm in the same manner allowed on high seas. Under UNCLOS, a warship on the high seas may carry out its whole array of activities including launching helicopters, turning on fire-control radars, and carrying out arms exercises. However, these and other activities (including fishing and research) are all prohibited when sailing in another country’s 12 nm territorial waters – a condition known as “innocent passage,” detailed under UNCLOS Part II, Article 19.