Japan-Philippines maritime delimitation talks: A geopolitical farce

Editor's note: Yu Minna, a special commentator for CGTN, is associate professor at the School of Law of Ocean University of China (OUC). The article reflects the author's opinions and not necessarily the views of CGTN.

On May 28, 2026, following a meeting between Japanese Prime Minister Sanae Takaichi and visiting Philippine President Ferdinand Marcos Jr., Tokyo and Manila issued a joint statement announcing the start of the so-called maritime delimitation talks of their respective exclusive economic zones (EEZ) and continental shelf.

In swift response, on May 29, Chinese Foreign Ministry Spokesperson Mao Ning stated that the area the two countries announced they will delimit is east of China's Taiwan island. China has an exclusive economic zone and a continental shelf in this area according to domestic law and international law, including the United Nations Convention on the Law of the Sea (UNCLOS). Japan and the Philippines' so-called maritime delimitation talks constitute a flagrant violation of China's maritime rights and interests, UNCLOS, and other international law and basic norms governing international relations.

The waters east of Taiwan island are by no means the private property of Japan and the Philippines

The waters east of Taiwan island carry China's maritime rights and interests extending into the Western Pacific and connect the high seas and the international seabed area. This region is by no means a "legal vacuum" that can be delimited exclusively by Japan and the Philippines.

To the north of this area, a dispute over the Diaoyu Dao and its affiliated islands persists between China and Japan, and the delimitation of the East China Sea remains unresolved. Geologically, the Diaoyu Dao and its affiliated islands are connected to the main island of Taiwan, separated from Japan's Ryukyu Islands by the Okinawa Trough, which plunges to depths of over 2,000 meters.

The Diaoyu Dao and its affiliated islands have been Chinese territory since ancient times. Although they were unlawfully seized by Japan, they were restored to China after World War II (WWII). China claims that its continental shelf in the East China Sea extends naturally to the Okinawa Trough (natural prolongation). Consequently, Beijing does not recognize the unilateral "median line" in the East China Sea put forward by Tokyo, which is based on Japan's illegal claims over China's Diaoyu Dao and its affiliated islands and Japan's southwestern remote islands. Japan's attempt to legitimize its illegal claims and squeeze China's lawful rights through maritime delimitation with the Philippines will inevitably exacerbate regional tensions and elevate the risk of geopolitical conflict.

To the south of this area, China and the Philippines share extensive overlapping maritime claims in the Bashi Channel. Located between China's Taiwan island and the Philippine archipelago, the Bashi Channel is an area where China enjoys an EEZ and a continental shelf. These rights overlap with the maritime claims asserted by the Philippines based on its archipelagic baselines.

By pursuing bilateral delimitation with Japan, Manila is attempting to bypass China to forcibly fix its northern maritime boundaries and create a fait accompli. This is a calculated attempt to "open a second battlefield" outside the South China Sea to unlawfully encroach upon China's maritime rights and interests.

To the east, Japan is exploiting Okinotori Rock to unlawfully annex areas of the high seas and the international seabed area. Okinotori consists of two isolated rocks in the deep Western Pacific. According to Article 121(3) of UNCLOS, rocks which cannot sustain human habitation or economic life of their own shall have no EEZ or continental shelf; every state is entitled to a territorial sea not exceeding 12 nautical miles at most.

However, Japan mischaracterizes these "rocks" as "islands" to claim a massive EEZ and continental shelf spanning over 40,000 square kilometers, attempting to swallow vast expanses of the high seas, the international seabed area, and the resources within.

Facing international scrutiny and pressure, Tokyo has adopted a detour tactic, seeking to bundle this illegal claim into maritime delimitation negotiations with Manila to secure de facto recognition. Such a political stunt – premised on a backroom deal that damages the collective interests of the international community – is destined to be a self-deluding farce.

Bilateral delimitation between Japan and the Philippines flagrantly violates international law

The closed-door, bilateral maritime delimitation conducted by Japan and the Philippines to the exclusion of China is a grave violation of international law.

First, it severely infringes upon China's lawful maritime rights as a coastal state. China holds indisputable sovereignty over the Taiwan island, the Diaoyu Dao and its affiliated islands, and Nanhai Zhudao (the South China Sea islands). In accordance with UNCLOS, China, as a coastal state, lawfully claims maritime entitlements including its EEZ and the continental shelf.

Ignoring these geographical and legal realities, Japan and the Philippines have bypassed China to conduct bilateral negotiations. The essence of their action is a malicious attempt to strip China of its legitimate status as a coastal state in these waters and openly deny China's sovereignty and maritime claims. This constitutes a fundamental violation of the purpose of UNCLOS.

Second, it violates the obligations regarding maritime delimitation under UNCLOS. Articles 74 and 83 of UNCLOS dictate that the delimitation of the EEZ and the continental shelf between states with opposite or adjacent coasts shall be effected by agreement on the basis of international law in order to achieve an equitable solution. The waters east of China's Taiwan Island represent a classic multilateral zone with overlapping entitlements.

By deliberately excluding China, the most critical stakeholder, from the negotiations, Japan and the Philippines are attempting to privately dispose of maritime areas involving China's sovereignty and sovereign rights. This "closed-door pie-cutting" robber logic entirely departs from the core requirement of UNCLOS for equitable delimitation, rendering all subsequent negotiations null and void from the very outset.

Third, it openly flouts the fundamental principle of third-party consent in international law. In the landmark "Monetary Gold" case, Italy and the United Kingdom brought a dispute before the International Court of Justice (ICJ) over gold looted by the Nazis. However, because Albania, the true owner of the gold, was absent and had not consented to the jurisdiction, the ICJ ultimately ruled that it could not adjudicate the case. The underlying logic of this precedent is self-evident in international law: No state or tribunal has the right to adjudicate or strip a third party of its legal rights without its consent.

Applying this to the current situation, the maritime areas east of Taiwan island are characterized by overlapping sovereign rights and intricate multilateral interests. For Japan and the Philippines to "cut the pie" in this maritime space, their technical premise and legal logic must inherently involve the unauthorized presumption and unilateral framing of the boundaries of China's lawful maritime rights in this area. Just as the ICJ lacked jurisdiction to rule due to the absence of Albania's consent, the closed-door delimitation by Japan and the Philippines, which completely excludes China, is a blatant trampling of the principle of third-party consent.

Finally, the bilateral negotiations and any subsequent arrangements cannot affect or diminish China's sovereignty and lawful claims. The maxim "Pacta Tertiis Nec Nocent Nec Prosunt" – a treaty does not create either obligations or rights for a third state without its consent – is a bedrock principle codified in the Vienna Convention on the Law of Treaties (VCLT). Article 35 of the VCLT further stipulates that an obligation arises for a third State from a provision of a treaty only if the parties to the treaty intend the provision to be the means of establishing the obligation and the third state expressly accepts that obligation in writing.

The maritime lines unilaterally drawn by Japan and the Philippines are, in essence, an attempt to impose on China limits that they themselves have defined. This amounts to a disguised deprivation of China's lawful rights, creating a false impression that Beijing is obligated not to cross these self-proclaimed lines, and even implies that China should relinquish its sovereignty over relevant islands and reefs. In the absence of China's explicit written consent, however, this arrangement is completely illegal, null, and void vis-à-vis China under international treaty law.

Geopolitical calculations can never override the rule of international law, nor can the backroom maneuvering between Japan and the Philippines shake China's sovereignty and maritime rights and interests. This geopolitical farce, built on sand and spun from thin air, will inevitably vanish and crumble before the unshakeable authority of international law.

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