Back to Basics in the South China Sea

The recent announcement that China has deployed advanced surface to air missiles on Woody Island in the Paracels island chain is, of course, only latest in series of developments that have brought increased attention to Chinese maritime and airspace claims in the South and East China Seas. But as the debate around Chinese activities grows more complex, a murky understanding of both Chinese claims and how they relate to international law and accepted international norms persists among the general public. It may, therefore, be useful to revisit some of the basics. Even as the questions are presented as highly technical and obscure, the fact remains that most of the law surrounding maritime claims is straightforward, even if the claims themselves are not.

For those coming somewhat recently to South China Sea issues, this article presents a brief primer on the law and issues surrounding China’s maritime claims.

United Nations Convention on the Law of the Sea (UNCLOS)

The United Nations Convention on the Law of the Sea (UNCLOS) is an international treaty with 167 states parties. Part II of the treaty lays out the privileges, duties, and responsibilities of ships and coastal states in waters near the sovereign territory of a coastal state, referred to as territorial seas, contiguous zones, and exclusive economic zones. Although not a state party to UNCLOS, the US recognizes the portions of UNCLOS regarding maritime claims as customary international law. In layman’s terms, this means that the United States supports and adheres to those portions of the treaty out of a sense of legal obligation because it represents what states are expected to do.

Under UNCLOS, in terms of the degree of control a state can exert in a given body of water the most important distinction is between inland waters and the seas. This distinction depends on a baseline, normally the low water line on a given beach or shore. (Though, there are exceptions to this, none are relevant in the South China Sea or East China Sea disputes). Water on the landward side of the baseline—such as bays, navigable rivers, and large lakes or inland seas—qualify as inland waters; water on the seaward side constitutes part of the seas. (UNCLOS Arts 5, 9, 10.) States have the same rights to control and regulate inland waters as they do over their own land. Inland waters are sovereign territory (UNCLOS Art 8), so any ship—including warships and other vessels owned by states—requires permission to enter inland waters. In contrast, the degree of control a state can exert over the seas varies depending on the distance from the baseline. The degree of regulation seeks to balance the rights of all states to use the seas as global commons, with the rights of coastal states to maintain security, extract resources, and regulate commerce in and from the sea adjacent to them.

From the baseline out to twelve nautical miles is referred to as territorial sea. (UNCLOS Art 3.) Here, the coastal state may regulate customs, immigration, sanitation, and the safety of navigation—such as the establishment of traffic separation schemes—as well as the protection of infrastructure and natural resources. (UNCLOS Art 21.) States may also exercise criminal jurisdiction over foreign vessels (except government vessels) for crimes that affect the peace of the coastal state, or the good order of the territorial sea. Civil jurisdiction is more limited—states may not board ships to exercise civil jurisdiction over people on board, but they may exercise civil jurisdiction to enforce liabilities or obligations incurred by the ship in the course of its passage. For example, if a non-government ship were to embark a pilot to transit a strait, but then refuse to pay the pilot, the coastal state could keep the ship from leaving until the debt was paid. (UNCLOS Arts 27-28.)

But a coastal state may not prevent the passage of any ship in their territorial sea. At a minimum, all ships are entitled to “innocent passage,” which is the transit of a vessel in a way that does not threaten the peace, good order, or security of the coastal state. In practice, this means that a ship must transit in a way that is “continuous and expeditious” and not engage in any activity not directed related to safely sailing through the waters in question, such as fishing, surveillance, military exercises, launching and recovering aircraft. All ships, including warships and other government vessels, enjoy the right of innocent passage. (UNCLOS Arts 17-19.) Submarines exercising the right of innocent passage must transit on the surface. (UNCLOS Art 20.) A coastal state may temporarily suspend innocent passage in order to conduct activities in their territorial sea which might be dangerous to passing ships, such as conducting weapons exercises, but such suspensions must be temporary and can only take place after being publicized. (UNCLOS Arts 24, 25.) Aircraft do not enjoy the right of innocent passage—with few exceptions—for example, international straits, or when declaring an emergency—they require permission to enter the airspace over territorial seas.

In addition to a territorial sea, a state may claim a contiguous zone out to 24 nautical miles, in which they may exercise the control necessary to enforce customs, immigration, and sanitary laws. (UNCLOS Art 33.) Except for these limited purposes, the coastal state cannot interfere with or impose conditions on passage or flight in the contiguous zone.

From 24 nautical miles to 200 nautical miles is the exclusive economic zone (EEZ). Within the EEZ, the coastal state has sovereign rights for the purposes of exploring, exploiting, conserving, and managing natural resources, including fish, oil, and minerals. The coastal state may exercise the degree of control necessary to enforce those rights, such as inspecting fishing vessels to ensure they have appropriate permits and are complying with regulations. Other states generally enjoy the same freedom of navigation and overflight in the EEZ as they do on the high seas, subject to the provision that they shall have ‘due regard’ for the rights and duties of the coastal state in the EEZ. (UNCLOS Arts 55-58.)

The area outside 200 nautical miles is known as the high seas (sometimes referred to as international waters). All ships and aircraft of any nation enjoy the right to sail or fly in the high seas without interference.

No, man—it’s an island

Unsurprisingly, UNCLOS defines islands. An island is “a naturally formed area of land, surrounded by water, which is above water at high tide.” Islands generate their own regime of state control—a territorial sea, etc. The exception is that a “rock which cannot sustain human habitation or economic life” (UNCLOS Art 121) of its own is not entitled to an EEZ, although it does generate a territorial sea. In practice, this has been interpreted to mean that, in order to have an EEZ, an island must have a naturally occurring source of fresh water.

Regardless of whether it can sustain habitation or economic life, in order to be an island, an area of land must be both naturally occurring and above water at high tide. Land that is submerged at high tide is considered to be a “low tide elevation.” (UNCLOS Art 13.) If such a feature occurs within breadth of the territorial sea, it may be used as a new baseline (i.e. the territorial sea extends 12 nautical miles seaward of the low tide elevation). If it falls outside the territorial sea, it generates no territorial sea, contiguous zone, or EEZ on its own. If the land is not naturally occurring, it is an artificial island. Like low tide elevations, artificial islands do not generate their own territorial sea, contiguous zone, or EEZ. (UNCLOS Art 60.) Unlike low tide elevations, artificial islands cannot be used to justify a new baseline, even if they occur in the territorial sea. (UNCLOS Art 12.)

China’s maritime and airspace claims

Although China is a state party to UNCLOS, the bulk of its disputed maritime and airspace claims are not consistent with or based on UNCLOS. Instead, they are based on the Chinese assertion of the “nine-dash line,” sometime called the U-shaped line or the “cow’s tongue,” due to its unique shape. This line, which encompasses most of the South China Sea has been described by official Chinese sources as marking “area[s] of China’s national sovereignty.” Although this statement remains ambiguous, it suggests that they regard the entirety of the region enclosed by the line as sovereign, a statement which would provide a stronger degree of control than any regime described under UNCLOS, except perhaps internal waters.

China interprets the “due regard” provision of the EEZ definition as prohibiting military activity inside their exclusive economic zone. According to this view, military ships and aircraft operating inside the EEZ should be limited to activities that would be consistent with innocent passage. This position is controversial and has not been widely accepted—only a handful of nations assert the right to limit foreign military activity beyond 12 nautical miles from the baseline, and of those, an even smaller group base that assertion on the claim that such activity is prohibited in the EEZ. The United States does not accept the Chinese position regarding military activity in the EEZ.

Many of the problematic claims in the South China Sea stem from contested claims of sovereignty, and not from a differing or excessive interpretation of UNCLOS. For example, the Paracel Island chain, where Woody Island is located, is claimed by China, Taiwan, and Vietnam. Some islands and reefs in the South China Sea are claimed by as many as five different nations. UNCLOS specifies the degree of control a coastal state is able to exert over waters around its territories, but it is silent about to whom the territory belongs in the first place. China’s nine-dash line claims and their disproportionate size relative to their neighbors are reminiscent of Thucydides’ observation that “the strong do what they will; the weak suffer what they must,” but these are questions of power and geopolitics, not technical issues related to the law of the sea.

In November 2013, China declared an Air Defense Identification Zone (ADIZ) in the East China Sea, which included the airspace over the contested Senkaku/Daiyou islands. There is no treaty that governs airspace in the same way that UNCLOS governs the seas; there is neither a specific legal basis for an ADIZ, nor any legal prohibition on establishing one. (The Convention on International Civil Aviation, known as the Chicago Convention is the closest thing to UNCLOS for airspace and does not mention ADIZs).

An ADIZ is an area of airspace in which a government has established a requirement that aircraft maintain communication and establish their identity in the interests of national security. “Requirement” in this instance is a term of art—if an aircraft fails to communicate or establish their identity, the only acceptable recourse is to attempt to establish communications and verify identity, either by repeated radio calls or by launching aircraft (usually fighters) to intercept and visually identify the unknown aircraft. In practice, the US and many other nations recognize the validity of an ADIZ as an extension of the right to regulate which aircraft may enter their airspace.

The Chinese East China Sea ADIZ differs from accepted practice in two important ways. First, it purports to apply to all aircraft, including those owned by states, such as military planes. And second, it requires that all aircraft passing through the ADIZ establish communications, rather than only those bound for China or Chinese territories. While these requirements are excessive, China does not have the resources to enforce them, since doing so would require intercepting dozens of commercial flights daily as they transit the outer edges of the ADIZ. In the case of government aircraft, such as US Air Force or Japanese Air Self Defense Forces, the establishment of the ADIZ may provide a pretext for Chinese aircraft to intercept and escort them which may lead to dangerously close encounters. However, such encounters occurred prior to the declaration of the ADIZ, as well, for example in an incident involving a US EP-3 reconnaissance aircraft in April 2001, or a more recent incident involving a P-8 aircraft in 2014, which occurred in international airspace outside the area of the ADIZ.

US FONOPS: Navigating competing legal claims

The US Navy routinely challenges maritime claims that are excessive by conducting Freedom of Navigation Operations (FONOPS). FONOPS can challenge claims ranging from countries that deny the right of warships to conduct innocent passage or (as China does) require prior notification, to countries that claim excessive territorial sea. In the case of the South China Sea, the challenge to successful FONOPS is not that China has made an excessive claim under UNCLOS, but that China has made a claim of sovereignty unrelated to UNCLOS through the nine-dash line in an area where US allies and other countries have claims that are consistent with UNCLOS. While the legal landscape is relatively clear, the strategic messaging is much less so. For example, when the USS LASSEN conducted a FONOP near Subi Reef in the Spratly Island chain, some interpreted the move as an assertion that China’s recent construction program did not change the character of Subi Reef from a low tide elevation—which would not generate a territorial sea—to an island, and were upset that LASSEN’s transit was consistent with innocent passage. That claim was complicated by the fact that Subi Reef lies within 12 nautical miles of Sandy Cay, a naturally occurring island claimed by China, the Philippines, Vietnam, and Taiwan. The complexity of the issue did not stem from obscure points of law—no amount of construction can change a low tide elevation into an island for purposes of UNCLOS, and China does not assert an explicit UNCLOS claim that Subi Reef is an island—but rather from the close proximity of multiple islands with competing sovereignty claims.

Chinese maritime power and maritime claims continue to expand in the South China Sea and East China Sea. International law governing these areas is well-established and relatively straightforward. Competing claims of sovereignty, however, make the application of straightforward principles a more challenging prospect.