On 28 February 2025, the Permanent Representative of China to the United Nations addressed a Letter to the UN Secretary-General which appears to largely be in response to the Letter dated 5 December 2024 from the Permanent Representative of the United States of America to the United Nations addressed to the Secretary-General.
In short, the USA Letter of 5 December 2024 referred to the 2022 study, Limits in the Seas No. 150, as well as 2022 State Practice Supplement, to emphasis the primary US position that the baseline provisions of UNCLOS are ‘comprehensive’, regulating the drawing of all baselines, including those pertaining to “continental States’ outlying archipelagos”. In the alternative, the US affirms that if the drawing of baselines pertaining to “continental States’ outlying archipelagos” is not regulated by the baseline provisions of UNCLOS, but rather customary international law, then the relevant rules of customary law must be demonstrative through State practice and opinio juris. The USA refutes that there is sufficient evidence in State practice and opinio juris to establish a customary legal basis for non-archipelagic States to establish straight baselines around outlying island groups.
The China Letter of 28 February 2025 affirms, first that the UNCLOS provisions on baselines are non-exhaustive and the “question of continental States’ outlying archipelagos was deferred”, and second, that the “practice regarding continental States’ outlying archipelagos [is] long-established in international law”. China rejects the findings of the US State Department Study, and affirms China’s position that the existing straight baselines at Xisha Qundao/Paracel Islands are consistent with international law and that “China has yet to draw its territorial sea baselines for other archipelagos”. To constitute an ‘archipelago’ in general international law, China suggests the maritime features must “constitute a legal whole”, with the conditions being “constitutes an entity in geographic, economic and political terms, and has been regarded as an entity respectively throughout history” (see, similarities to Article 46(b) of UNCLOS which defines archipelago for the purposes of UNCLOS).
Note, it is the shared position of both States, evident in the letters, that only Archipelagic States may establish archipelagic baselines, as provided in Part IV of UNCLOS. Continental States are by definition not Archipelagic States (Article 46 of UNCLOS) and therefore may not establish archipelagic baselines as governed by UNCLOS (Article 47 of UNCLOS; South China Sea Award (2016) para 573). The differences concern whether there are (a) lawful baselines circumstances outside of UNCLOS, and (b) whether this includes straight baselines around ‘archipelagos’ by Non-Archipelagic States (on both, note South China Sea Award (2016) paras 575-576).
De Maribus 