A league at sea is three nautical miles, or about the distance from Curtis Island Light to Mark Island.

That is about the distance a cannonball could be launched from shore during the age of sail and exploration, when the European powers and America jostled for domination of coastlines and colonies in Asia.

Not by coincidence, and by international custom, during that same age the limit of a coastal country’s “territorial sea” was set at three nautical miles from shore. Within that margin the coastal country had the power to bar foreign ships. Outside the territorial sea, was “mare liberum,” legal Latin for the “freedom of the high seas,” where ships under all countries’ flags could pass, or fish, unimpeded by national law.

With the arrival of steam power and modern gunnery and the deployment of Western and Japanese “gunboat diplomacy” in Asia, many countries reciprocated in extending the boundary of territorial seas to 12 nautical miles (about the distance across Penobscot Bay from Rockport to Deer Isle).

In 1945, alerted to the feasibility of drilling for oil in the Gulf of Mexico, President Truman unilaterally declared to a war-exhausted world that “henceforth it would be American policy” that the United States possessed an “exclusive economic zone” to exploit (and to exclude other nations from exploiting) all resources within 200 nautical miles of its shores. Soon other coastal countries made similar claims. 

In 1982, the United Nations Convention on the Law of the Sea came into force. The Convention binds all signatory nations to respect territorial seas out to 12 nautical miles and exclusive economic zones out to 200 nautical miles. Signatory nations also agree that their disputes under the Convention must be resolved by arbitration.

Every significant coastal nation, including China, has signed the treaty — except the United States. The Reagan- era Senate could not accept certain clauses on deep-sea mining. Although not a party, the US endorses and observes the Convention’s provisions on territorial seas and exclusive economic zones.

Which brings us to the South China Sea.

Through this sea of a million square miles passes half the world’s merchant shipping, a third of global oil tankers, almost all of China’s imports from the Middle East, a tenth of the world’s fishing catch, and frequent missions of the US Pacific Fleet. 


For centuries, fishermen and merchants and gunboats from Vietnam, Malaysia, the Philippines and China have plied its waters, run afoul of its half-submerged rocks, and, especially in recent decades, asserted claims of national jurisdiction over its tiny islands and atolls.

China now claims almost every tiny land feature in the entire sea. This includes far-flung rocks and reefs hundreds of miles from its mainland and much closer to the coasts of Vietnam and the Philippines and Malaysia. Those other countries, not surprisingly, claim the same rocks and reefs. China makes sure that all Chinese passports now include a “nine-dash line” to demarcate its vague and vast maritime claims.

Meanwhile, in just the past few years, in several corners of that sea, Chinese armadas of dredgers and contractors guarded by Chinese naval vessels have constructed artificial islands — with military airstrips and sophisticated radar — above once pristine coral atolls. And in 2013, the Chinese “coast guard” skirmished with and expelled a Philippine garrison from a tiny island claimed by both countries.

Soon thereafter, the Philippines invoked the UN Convention to bring multiple claims against China in the Permanent Court of Arbitration at The Hague. At hearings held in the stained-glass splendor of the Peace Palace, the Chinese side was occupied only by three empty chairs. China has refused to join the proceedings, on the (legally strong) grounds that the Court had no jurisdiction under the Convention to decide claims of sovereignty.

The Philippine claims, however, were drafted to avoid any decision on sovereignty. Instead, the Philippines asked the Court (on even stronger legal grounds) to clarify the status of certain low-lying rocks and reefs and atolls, and the status of the artificial islands constructed by China. Specifically, the Court considered whether any of these could qualify as “islands” under the Convention, for purposes of defining a territorial sea or exclusive economic zone.

Tuesday this week, the Court announced its decision. It unanimously held in favor of the Philippines. It strongly rebuked China for its actions, particularly the building of artificial islands.

This is China’s first involvement with an international legal tribunal. As a legal and diplomatic matter for China, and its assertive President Xi Jinping, this unambiguously negative ruling is a resounding loss of face.

A diplomatic or military crisis may soon take the name of one of these tiny dots on the map: Fiery Cross, the Paracels, the Spratleys, Scarborough Shoals. Or, maybe, Mischief Reef.