UNCLOS stipulates that the deadline for the submission of information on the outer limits of the continental shelf to the CLCS was before 13 May 2009 (See SPLOS/72). In the South China Sea, Indonesia lodged its submissions on the outer limits of the continental shelf beyond 200 nm in the northwest area of Sumatra Island to the CLCS on 16 June 2008; Viet Nam's partial submission in the northern area of the South China Sea (VN-N) on 6 May 2009; the joint submission from Malaysia and Viet Nam on 7 May 2009; and Malaysia's partial submission on 12 December 2019. The Philippines submitted its first partial submission on the outer limits of its continental shelf outside the South China Sea in the Benham Rise Region on 8 April 2009, which was favorably acted upon by the CLCS in its Recommendation issued on 12 April 2012. As a member state of UNCLOS, the Philippines has the right to implement Article 76 of the Convention and Annex I of the Rules of Procedure of the CLCS (CLCS/40, Rev. 1) for the extended continental shelf if the geographical and geological structures of the shelf meet the legal requirements. The Philippines has the right to have new submissions because it has provided the preliminary information before the deadline.

The Philippine Submission: Third Round of Note-Verbal Battle?

The map of the outer limit of the continental shelf claims in the South China Sea, prepared by the East Sea Institute, Diplomatic Academy of Vietnam, 17 June 2024

Why has the Philippines submitted its extended continental shelf file in the South China Sea 15 years after the Convention's deadline? The answer can only come from the Philippine administration under the Marcos’ presidency, which has pursued a shift to a more pronounced transparency policy on the South China Sea. The Philippines’ submissions would have some calculations. Firstly, the Marcos administration would aim to assert the validity of the Tribunal Award of 12 July 2016 on the Philippines vs. China case, which allows for the expansion of the continental shelf from the mainland while confining the maritime features in the Spratlys each to a maximum of 12 nautical miles of territorial waters. Secondly, the submission would be designed to reject the validity of China's nine-dash line claim. Thirdly, Manila would affirm the validity of the Philippines' archipelagic baseline of 2012, which has been revised to align more closely with UNCLOS by excluding the Kalayaan Area from the scope of an archipelagic state. Fourthly, it would consider the possibility of invoking Article 5 of the 1951 Mutual Defense Treaty (MDT), in which the US is obligated to protect Philippine armed forces, public vessels, aircraft (including those of its coast guard) from armed attack in the South China Sea. U.S. Secretary of State Antony Blinken on 19 June 2024 spoke with Philippine Foreign Affairs Secretary Enrique A. Manalo about China's actions against the Philippines in the South China Sea "undermine regional peace and stability and underscored the United States.” Fifthly, it would give facilitation to the stalled negotiations on the Code of Conduct (COC). Last but not least, the move would leverage the presence of the Philippine member in the CLCS. Mr. Efren Perez Carandang, a member of the Commission for the term 2023-2028, was acknowledged for providing advice in the preparation of this submission.

The Philippines' submission may encounter several challenges. First, the seabed geological conditions of the archipelagic state are unfavorable for defining the extension beyond its territorial sea 'throughout the natural prolongation of its land territory to the outer edge of the continental margin,' due to the presence of the Palawan Trench, which creates a disruption. This may be why the Philippines has opted to use the method of drawing arcs not exceeding 60 nautical miles from the foot of the slope (FOS) point, in accordance with Paragraph 4(a)(ii) of Article 76, instead of the formula based on percentage of sediment thickness. The submission acknowledges that this formula was not utilized due to insufficient sediment thickness data in the West Palawan Region (WPR).

Second, the southern part of the submission extends from the Sabah, which is subject to a sovereignty dispute with Malaysia and the Vietnam-Malaysia joint submission.

Third, the submission may potentially overlap with Vietnam's submission in the central region, where Vietnam declared the reservation of its sovereign rights in opposition to Malaysia's extended continental shelf in December 2019.

Fourth, the dispute over the sovereignty of the Spratly features remains unresolved, raising the question of maritime delimitation of the sea-bed of territorial seas of those features with the Philippine's continental shelf claims. 

Fifth, combining unilateral continental shelf claims with the 2016 ruling on a 12-nautical-mile territorial sea for features in the Spratly suggests that the South China Sea may have high seas but lacks a seabed area designated as the common heritage of mankind. This situation poses challenges in establishing an appropriate marine management regime given the differing status of maritime zones.

The bright spot in the Philippines' submission is its acknowledgment of the existence of previous submissions by Vietnam and Malaysia, rather than rejecting them, and its willingness to discuss the delimitation of maritime boundaries with the relevant states. The submission has not named China for negotiations on the continental shelf.

The reactions of the interested states would be drastic. Malaysia maintains its claim to Sabah. Its note verbale on 27 June 20224 recalled that “The state of Sabah has and always been an integral part of Malaysia and has been recognized by the United Nations and the international community, as part of Malaysia, since the formation of the Federation of Malaysia on 16 September 1963. The Republic of the Philippines claims sovereignty over Sabah is incompatible with its erga omnes obligation to recognise and uphold the legitimate exercise of the right of self – determination by the people of Sabah in 1963. Thus, it is clear that the Republic of the Philippines’ claim to Sabah has no basic whatsoever under international law”.  

China submitted preliminary survey findings on the outer limits of its continental shelf in the East China Sea to the Commission on the Limits of the Continental Shelf (CLCS) on 11 May 2009. However, in the South China Sea, China has not shown an intention to claim an extended continental shelf. This stance could be explained by its expansive nine-dash line and Nanhai Zhudao, which would cover almost all the waters and seabed of the South China Sea. On 17 June 2024, China warned that “The Philippines’ unilateral submission on the extent of its undersea shelf in the South China Sea infringes on China’s sovereign rights and jurisdiction, violates international law, including the United Nations Convention on the Law of the Sea (UNCLOS), and goes against the Declaration on the Conduct of Parties in the South China Sea.” On the same day, clashes occurred between Philippine supply vessels and Chinese Coast Guard ships around the Second Thomas Shoal. A day later, on 18 June 2024, the Chinese note verbale consisted on the indisputable sovereignty over Nanhai Zhudao and the adjacent waters and it enjoys sovereign rights and jurisdiction over the relevant waters as well as the seabed and subsoil thereof.

On 20 June 2024, Vietnam declared that it reserves all its rights and interests under international law, especially UNCLOS 1982, and expressed its readiness to discuss with the Philippines to find and reach a solution that aligns with the interests of both countries. Vietnam's reaction is likely to be more subdued, because its position is to grant the features in the Spratly Islands only a 12-mile territorial sea. Other overlapping continental shelf claims are not related to unresolved sovereignty issues. For that reason, the submission would signal the beginning of the third round of the note verbale battle of which the first and second rounds arose after 2009 and 2019 submissions respectively. The maritime limits, including the overlapping outer limits of the continental shelf in the South China Sea, with distances between opposite coasts of no more than 700 nautical miles, need to be agreed upon by the countries involved and are not under the jurisdiction of the CLCS. In the immediate future, the Philippines may consider a withdrawal from its objection to the Vietnam-Malaysia joint submission and negotiation with these two countries to find an acceptable solution.

Nguyen Hong Thao,

Diplomatic Academy of Vietnam