The atoll of Okinotorishima (known also as Oki-no-Tori Shima Island and Parece Vela) is Japan’s southernmost territory, located at 20° 25’ north latitude, 136° 04’ east longitude. It is the only Japanese territory south of the Tropic of Cancer, and lies to the south of Hong Kong and Taiwan, at about the same latitude as Hawaii. Okinotorishima is located approximately halfway between Okinawa Main Island and Guam Island, both of which house U.S. military bases.
Okinotorishima is a long and narrow coral atoll, about 4.5 km from east to west and 1.7 km from north to south, with a circumference of 11 km. It has two landforms, Kitakojima and Higashikojima, which are exposed above sea level at high tide.
According to the United Nations Convention on the Law of the Sea (UNCLOS), when the Commission on the Limits of the Continental Shelf (CLCS) deems that a continental shelf is topographically and geologically continuous for more than 200 nautical miles, a coastal state may define a continental shelf beyond 200 nautical miles. Japan began investigating its continental shelf in 1983 and applied to the CLCS for a continental shelf extension in 2008, receiving the CLCS recommendations in 2012. The CLCS recommendations granted the continental shelf extension for four out of seven sea areas that Japan had applied for, thus recognizing an extension of approximately 310,000 sq km, equivalent to about 80 percent of the Japan’s land area.
At the same time, the CLCS refrained from issuing any recommendations regarding the “Southern Kyushu-Palau Ridge” located south of Okinotorishima, saying that it was not in a position to act until the issue of Okinotorishima’s international legal status (“island” or “rock” under international law) is resolved, with reference to notes verbales submitted by the Chinese and South Korean governments.
In a note verbale (CML/2/2009) to the Secretary-General of the UN on February 6, 2009, the Chinese government states that “the so-called Oki-no-Tori Shima Island is in fact a rock as referred to in Article 121(3) of the Convention” and that “Available scientific data fully reveal that the rock of Oki-no-Tori, on its natural conditions, obviously cannot sustain human habitation or economic life of its own, and therefore shall have no exclusive economic zone or continental shelf.”
The South Korean government also wrote a note verbale (MUN/04/09) to the Secretary-General of the UN, dated February 27, 2009, stating that “the Oki-no-Tori Reef should be regarded as a rock as defined in article 121(3) of UNCLOS, and therefore should not have an exclusive economic zone, a continental shelf, or a continental shelf beyond 200 nautical miles.”
Hypothetically, assuming that Okinotorishima is not an “island” but a “rock” under international law, as the Chinese and South Korean governments claim, and that it is not permissible to use it as base point for defining an EEZ and continental shelf, that would mean that the waters surrounding Okinotorishima, which is a Japanese EEZ and continental shelf are high seas. In other words, the implication would be that all countries are quite free to conduct “marine scientific research” and military exercises in the West Pacific Ocean area centering on Okinotorishima in accordance with the principle of the “freedom of the high seas.”
The Japanese government is of the opinion that Okinotorishima is historically established to be an island, thus making it possible to define EEZ with the island as a base point. In connection with the ratification of UNCLOS in 1996, Japan enacted the “Act on Exclusive Economic Zone and Continental Shelf” (EEZ Act) and defined an EEZ of 200 nautical miles from the baseline around Okinotorishima. Later, the Japanese government built a lighthouse to enable the safe navigation of ships and operation of fishing vessels. The lighthouse began operating in March 2007.
The Chinese and South Korean governments are not disputing that Okinotorishima is Japanese territory. What they are objecting to is the vast EEZ and continental shelf that Japan has defined in the waters surrounding the atoll, as well as the vast continental shelf that Japan is trying to expand beyond 200 nautical miles. In other words, that are objecting to Japan possessing and exercising sovereign rights and jurisdiction in that sea area. Coastal states with EEZ possess sovereign rights with regard to marine biological resources and seafloor mineral resources as well as jurisdiction to regulate marine scientific research and the like.
China has been advancing into the South China Sea since the 1970s, the East China Sea since the 1980s, and the West Pacific Ocean since the turn of the 21st century. China frequently conducts marine scientific research and military exercises in the waters surrounding Okinotorishima in the middle of the West Pacific Ocean.
More recently, on July 9, 2020, patrol vessels of the Japan Coast Guard (JCG) confirmed that a Chinese oceanographic survey vessel was launching observation equipment into the sea in the Japanese EEZ approximately 310 north-northwest of Okinotorishima. Conducting marine scientific research without the consent of the EEZ coastal state is a violation of international law (UNCLOS Article 246 (2) violation). The JCG issued a warning and demand to the Chinese survey vessel, insisting that “It is not allowed to conduct survey activities in Japanese EEZ without our prior consent. We insist that you halt the survey.” After repeatedly recovering the observation equipment, moving to a different sea area in the Japanese EEZ, and launching the equipment into the sea again there, the Chinese survey vessel existed the Japanese EEZ on July 27.
Guam, which has a nuclear submarine base of the United States Navy, is located in the West Pacific Ocean area is home to Guam. It is thought that the reason why China claims that Okinotorishima is not an island but a rock and denies that the waters surrounding the island are Japan’s EEZ, is so that it can freely collect data about seafloor topography, water temperature, tidal currents, and so on, with the ultimate goal of preventing the U.S. Navy from sortieing in the event of a Taiwan emergency.
What matters for Japan is prevent Chinese survey vessels and warships from conducting those research activities in Japan’s EEZ around Okinotorishima. This will require Japan to regulate Chinese research activities in Japan’s EEZ in accordance with Japanese domestic law, as well as to step up patrols in the waters surrounding Okinotorishima to ensure that those regulations are enforced.
TSURUTA Jun is an associate professor at Meiji Gakuin University.