Asia Defense

China’s Baselines Around the Offshore Archipelago

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Asia Defense

China’s Baselines Around the Offshore Archipelago

Baselines are the starting point for China’s attempts to claim sea areas.

China’s Baselines Around the Offshore Archipelago

A Philippine supply boat, center, maneuvers around Chinese coast guard ships as they tried to block its way near Second Thomas Shoal, locally known as Ayungin Shoal, at the disputed South China Sea on Aug. 22, 2023.

Credit: AP Photo/Aaron Favila, File

On July 13, 2016, the day after an international tribunal issued the South China Sea Arbitration Award (Merits) in response to a Philippine request for arbitration, the Chinese government released a white paper titled “China Adheres to the Position of Settling Through Negotiation the Relevant Disputes between China and the Philippines in the South China Sea.” In this paper, China claimed that, in accordance with Chinese domestic law as well as international law such as the United Nations Convention on the Law of the Sea (UNCLOS), it possesses internal waters, a territorial sea, a contiguous zone, an exclusive economic zone (EEZ), and a continental shelf around Nanhai Zhudao, or the South China Sea Islands. A similar argument was made in “The South China Sea Arbitration Awards: A Critical Study,” which presented research findings of the Chinese Society of International Law in 2018.

When China establishes sea areas such as internal waters, territorial sea, contiguous zone, EEZ, and continental shelf in the South China Sea, the starting point for that is the establishment of baselines.

Normal Baselines and Straight Baselines

When it comes to establishing baselines, which serve as criteria for defining the range of internal waters, territorial seas, and EEZs, UNCLOS recognizes the establishment of “normal baselines” and “straight baselines.”

On normal baselines, Article 5 of UNCLOS stipulates: “Except where otherwise provided in this Convention, the normal baseline for measuring the breadth of the territorial sea is the low-water line along the coast as marked on large-scale charts officially recognized by the coastal State.” The low-water line is the boundary line between water and land when the tide goes out.

Meanwhile, for straight baselines, Article 7, Paragraph 1, of UNCLOS stipulates: “In localities where the coastline is deeply indented and cut into, or if there is a fringe of islands along the coast in its immediate vicinity, the method of straight baselines joining appropriate points may be employed in drawing the baseline from which the breadth of the territorial sea is measured.” In addition, according to Article 7, Paragraph 3, “The drawing of straight baselines must not depart to any appreciable extent from the general direction of the coast, and the sea areas lying within the lines must be sufficiently closely linked to the land domain to be subject to the regime of internal waters.”

The sea areas on the land side of these baselines are defined as “internal waters” under international law. Internal waters are part of the areas that belong to coastal states, and just like territory, the coastal states exercise full sovereignty there.

Baselines Under UNCLOS: Archipelagic Baselines

In Article 46(a) UNCLOS also recognizes the establishment of straight archipelagic baselines that connect the islands and reefs on the outermost edges of the archipelago in the case of an “archipelagic state” that consists of one or more “archipelagos” wholly (Article 47, Paragraph 1). UNCLOS states that “archipelago” means “a group of islands, including parts of islands, interconnecting waters and other natural features which are so closely interrelated that such islands, waters and other natural features form an intrinsic geographical, economic and political entity, or which historically have been regarded as such” (Article 46 (b)).

The sovereignty of an archipelagic state extends to the waters enclosed by the archipelagic baselines, described as archipelagic waters, regardless of their depth or distance from the coast (Article 49, Paragraph 1). This sovereignty extends to the air space over the archipelagic waters, as well as to their bed and subsoil, and the resources contained therein (Article 49, Paragraph 2).

A state that does not fall under the definition of “archipelagic state,” such as a state with continental territories, may not establish straight archipelagic baselines based on Article 47, Paragraph 1 even if it possesses an offshore archipelago.

China’s Baselines

China has established straight baselines that surround the islands in the South China Sea as a single unit, and it is possibly attempting to turn the vast sea areas on the land side of these baselines into “internal waters.” Even though China does not satisfy the definition of an “archipelagic state” according to UNCLOS, it may be trying to encircle offshore islands in the South China Sea as a single unit through straight baselines.

China announced in a Note Verbale to the Secretary-General of the United Nations in August 2021 that “the regime of continental states’ outlying archipelagos is not regulated by UNCLOS, and the rules of general international law should continue to be applied in this field.” This is China pointing the limited scope of UNCLOS regulations, whereas the South China Sea Arbitration Award recognized them to be “comprehensive.”

In reality, China announced the “Declaration of the Government of the People’s Republic of China on the baselines of the territorial sea” in May 1996, establishing baselines that encircle the Paracel Islands in the South China Sea as a single unit. The declaration stipulates that “the Government of the People’s Republic of China will announce the remaining baselines of the territorial sea of the People’s Republic of China at another time.” To date, no such baselines have been established (or been made public) for islands other than the Paracel Islands in the South China Sea.

Moreover, on September 12, 2012, China announced “the Statement of the Government of the People’s Republic of China on the Baselines of the Territorial Sea of Diaoyu Dao and its Affiliated Islands” and established baselines around the Senkaku Islands (known in China as the Diaoyu Islands). The statement includes a list of the geographic coordinates for the base points used to establish the baselines as well as a nautical chart. On September 13, 2012, one day after this statement was issued, China submitted a chart and a list of geographical coordinates in accordance with Article 16, Paragraph 2, of UNCLOS to the U.N. secretary-general.

Responding to China’s establishment of baselines around the Senkaku Islands and the submission to the U.N. secretary-general, the Japanese government sent the following “communication” to the UN Secretary-General on September 24, 2012: “There is no doubt that the Senkaku Islands are an inherent part of the territory of Japan in light of historical facts and based upon international law. The Senkaku Islands are under the valid control of the Government of Japan. This action by the People’s Republic of China concerning the Senkaku Islands, a part of the territory of Japan, is totally unacceptable and legally invalid.”