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Phạm Văn Lừng wrote this article in Vietnamese and published it in Luat Khoa Magazine on March 12, 2025. Đàm Vĩnh Hằng translated it into English for The Vietnamese Magazine.

On Nov. 8, 2024, Philippine President Ferdinand Marcos Jr. signed two significant pieces of legislation—the Philippine Maritime Zones Act and the Philippine Archipelagic Sea Lanes Act—to clarify his country's maritime claims. [1]

While these laws are presented as consistent with the United Nations Convention on the Law of the Sea (UNCLOS) and the 2016 Permanent Court of Arbitration (PCA) ruling, they create new legal challenges, particularly for Việt Nam. [2]

The Vietnamese Foreign Ministry spokesperson, Phạm Thu Hằng, responded on Nov. 21, 2024, by reiterating Việt Nam’s sovereignty over the Paracel and Spratly Islands and calling for respect for UNCLOS.

On the surface, since both countries claim to adhere to international law, their positions seem aligned. However, Việt Nam's official reaction failed to address a crucial issue raised in the new Philippine law: the legal status of low-tide elevations (LTEs) within the country’s exclusive economic zone (EEZ).

The Philippines' Claim on Low-Tide Elevations The crux of the issue lies in Article 7 of the new Philippine Maritime Zones Act, which asserts:

“All other low-tide elevations within 200 nautical miles from the archipelagic baselines shall form part of the Philippines’ exclusive economic zone.” [3]

To understand the legal challenge this poses, it is essential to refer to UNCLOS. Article 13 defines a low-tide elevation (LTE) as a naturally formed land area that is above water at low tide but submerged at high tide. [4]

Which low-tide elevations does Việt Nam currently occupy within the Philippines’ exclusive economic zone (EEZ)? They are Núi Le Reef ( Cornwallis South Reef ) and Tốc Tan Reef ( Alison Reef ). [5] [6]

China, meanwhile, occupies two low-tide elevations inside the Philippine EEZ: Mischief Reef ( Đá Vành Khăn ) and Hughes Reef ( Đá Tư Nghĩa ).

From the standpoint of national interest, Việt Nam will almost certainly oppose the Philippines’ claim. But from the perspective of international law, the issue is far more complex.

Low-Tide Elevations in the 2016 Ruling In the Philippine Baselines Law , Manila does not provide a legal basis for asserting sovereignty over low-tide elevations within its exclusive economic zone (EEZ).

However, the legal foundation for the Philippines’ position can be understood as stemming from the 2016 ruling of the Permanent Court of Arbitration (PCA).

The PCA reasoned that “territory,” by definition, must be “land territory,” meaning land that is permanently above water at high tide. Such areas include mainland territory, islands, or other permanently above-water features. Low-tide elevations, therefore, are not considered “territory.” Because they are not “territory,” they cannot be subject to acquisition under international law governing territorial sovereignty.

In paragraph 1040 of its 2016 Award, the PCA affirmed that Mischief Reef ( Đá Vành Khăn ) is a low-tide elevation, and therefore no state can acquire sovereignty over it. [7]

Similarly, regarding Subi Reef ( Đá Xu Bi ), Gaven Reef ( Đá Ga Ven ), and Second Thomas Shoal ( Bãi Cỏ Mây ), paragraph 1203 of the 2016 Award affirmed that these features are low-tide elevations and do not belong to any state. [8] However, paragraph 309 of the Award notes that if low-tide elevations are located within the territorial sea or continental shelf of a coastal state, they fall under that state’s sovereignty. [9]

While the PCA did not issue rulings on sovereignty over geographic features, researcher Phạm Ngọc Minh Trang, in an article published by the Asia Maritime Transparency Initiative (AMTI), argued that logically, Mischief Reef belongs to the Philippines. This is because the feature meets two conditions: (1) it is a low-tide elevation, and (2) it lies within the Philippines’ EEZ and continental shelf. [10]

Does Việt Nam Control Low-Tide Elevations Within the Philippine EEZ? According to information from AMTI, Núi Le Reef ( Đá Núi Le ) and Tốc Tan Reef ( Đá Tốc Tan ), currently controlled by Việt Nam, may satisfy the same two conditions: (1) in their natural state, prior to Việt Nam’s construction of military outposts, they were low-tide elevations, and (2) they lie within the Philippines’ EEZ and continental shelf. [11]

This presents a difficult challenge for Việt Nam.

Articles 7 and 13 of UNCLOS provide regulations on low-tide elevations, including when they may be used as base points and whether they generate territorial seas. However, UNCLOS does not address the issue of sovereignty over such features. [12]

So why did the PCA declare that low-tide elevations cannot be considered “territory” for purposes of sovereignty, but if located within a state’s waters, they fall under that state’s control?

Although UNCLOS does not contain explicit provisions on sovereignty over low-tide elevations, international case law carries strong legal authority. Prior to the PCA’s 2016 Award, there had already been similar rulings.

In paragraph 26 of its 2012 judgment in the maritime and territorial dispute between Nicaragua and Colombia, the International Court of Justice (ICJ) established precedent that low-tide elevations are not territory subject to sovereignty claims. [13]

Earlier, in 2001, in the case between Qatar and Bahrain, the ICJ reached the same conclusion. Paragraph 205 of the 2001 judgment stated that no rule of international law recognized low-tide elevations as “territory.” Paragraph 206 further clarified that under relevant provisions of UNCLOS, it can be inferred that low-tide elevations do not have the legal status of “territory” in the way islands do. [14]

Thus, the principle that low-tide elevations are not territory subject to sovereignty acquisition was declared twice by the ICJ—in 2001 and 2012—and reaffirmed by the PCA in its 2016 ruling in the Philippines v. China case.

Alongside treaty law, international case law has significant legal weight. For this reason, Việt Nam cannot disregard the PCA’s 2016 Award, nor the Philippines’ claims to low-tide elevations within its 200-nautical-mile EEZ and continental shelf.

How Will Việt Nam Handle Low-Tide Elevations in the Philippine EEZ? From a practical standpoint, Việt Nam is unlikely to relinquish sovereignty claims over these features, since it controls them in fact and stations troops at Núi Le Reef and Tốc Tan Reef.

In 2016, Việt Nam issued a statement on low-tide elevations referenced in the PCA’s Award. However, in its declaration (paragraph 4.ii.), Việt Nam only addressed the 12-nautical-mile territorial sea generated by such features, without discussing whether they could be considered “territory” subject to sovereignty claims. [15]

Việt Nam also does not face disputes over low-tide elevations within its own EEZ that are claimed by another state, such as China. Therefore, if Hà Nội chooses to ignore this detail in the PCA’s 2016 Award (and ICJ precedent), as well as the Philippines’ claims, it would not suffer immediate loss.

Legally, however, if Việt Nam publicly rejects this detail in the PCA’s Award (and ICJ precedent) and the Philippines’ position, it could create a “precedent” for China to more brazenly dismiss other international rulings that protect Việt Nam’s interests.

Most likely, Việt Nam will weigh “benefits versus costs” in approaching this issue. It is not an easy equation to solve. This may explain why Việt Nam’s recent response to two new laws passed by the Philippines came in the form of a deliberately vague and general statement.

References: 1. Gomez, J. (2024, November 8). Philippine president angers China with new laws to demarcate South China Sea territories | AP News . AP News. https://apnews.com/article/philippine-maritime-zones-act-archipelagic-sea-lanes-act-south-china-sea-4ecec3f00ab9367d948e5af3959aea21

2. Loan, T. (2024, November 21). Việt Nam nói về các bước đi của Philippines, Trung Quốc ở Biển Đông. Báo Điện Tử Tiền Phong . https://tienphong.vn/viet-nam-noi-ve-cac-buoc-di-cua-philippines-trung-quoc-o-bien-dong-post1693638.tpo

3. REPUBLIC ACT NO. 12064 – AN ACT DECLARING THE MARITIME ZONES UNDER THE JURISDICTION OF THE REPUBLIC OF THE PHILIPPINES – Supreme Court E-Library . (n.d.). https://elibrary.judiciary.gov.ph/thebookshelf/showdocs/2/98027

4. UNITED NATIONS CONVENTION ON THE LAW OF THE SEA . (n.d.). https://www.un.org/depts/los/convention_agreements/texts/unclos/part2.htm

5. Cornwallis South Reef | Asia Maritime Transparency Initiative . (2022, April 4). Asia Maritime Transparency Initiative. https://amti.csis.org/cornwallis-south-reef/

6. Alison Reef | Asia Maritime Transparency Initiative . (2022, April 4). Asia Maritime Transparency Initiative. https://amti.csis.org/alison-reef/

7. Cases | PCA-CPA . (n.d.). https://pca-cpa.org/en/cases/7/

8. See [7].

9. See [7].

10. Pham Ngoc Minh Trang. (2024, January 23). Second Thomas Shoal: A Legal Perspective | Asia Maritime Transparency Initiative . Asia Maritime Transparency Initiative. https://amti.csis.org/second-thomas-shoal-a-legal-perspective/

11. See [5] và [6].

12. See [4].

13. Territorial and Maritime Dispute (Nicaragua v. Colombia) – The Court finds that Colombia has sovereignty over the maritime features in dispute and draws a single maritime boundary | INTERNATIONAL COURT OF JUSTICE . (n.d.). https://www.icj-cij.org/node/102086

14. Judgment of 16 March 2001 | INTERNATIONAL COURT OF JUSTICE . (n.d.). https://www.icj-cij.org/node/103159

15. Ministry of Foreign Affairs of the Socialist Republic of Viet Nam. (2013). Statement Of The Ministry Of Foreign Affairs Of The Socialist Republic Of Viet Nam Transmitted To The Arbitral Tribunal In The Proceedings Between The Republic Of The Philippines And The People’s Republic Of China. In Arbitral Tribunal In The Proceedings Between The Republic Of The Philippines And The People’s Republic Of China. https://iuscogens-vie.org/wp-content/uploads/2018/03/statement-of-mofa-of-vietnam-to-the-tribunal.pdf