On May 28, 2026, during the Philippine President’s visit to Japan, the two countries issued a joint statement announcing the formal launch of “bilateral negotiations” on the delimitation of their exclusive economic zones and continental shelves. These so‑called “delimitation negotiations” focus on the waters east of China’s Taiwan Island, severely infringing upon China’s sovereign rights, maritime rights and interests, blatantly violating international law and basic norms of international relations, and constituting a typical political scheme disguised as “maritime delimitation.”

I. Three Layers of Illegality in the Japan‑Philippines “Delimitation Talks”

First, the talks violate the Law on the Exclusive Economic Zone and the Continental Shelf of the People’s Republic of China. Article 2 of this domestic law clearly defines the scope of China’s EEZ and continental shelf. As an inalienable part of China’s territory, the waters east of Taiwan Island naturally extend from the island’s land territory seaward and entirely belongs to China’s EEZ and continental shelf. Japan and the Philippines have no right to conduct any “delimitation negotiations” in waters under China’s jurisdiction.

Second, the talks violate the United Nations Convention on the Law of the Sea (UNCLOS). Under the principle of natural prolongation of the continental shelf in Article 76 of UNCLOS, China’s land territory naturally extends to the waters east of Taiwan Island, where China enjoys sovereign rights and jurisdiction in accordance with international law. By launching “delimitation negotiations” in disregard of China’s maritime rights, Japan and the Philippines have seriously contravened the spirit of understanding and cooperation and the purpose of promoting peaceful uses of the seas and oceans stipulated in Articles 74, 83 and the preamble of UNCLOS.

Third, the negotiations violate the fundamental international law principle that treaties shall not bind third States. Article 34 of the Vienna Convention on the Law of Treaties (VCLT) states that “a treaty does not create either obligations or rights for a third State without its consent.” Even if Japan and the Philippines probably reach a delimitation agreement in the future, such an agreement would in essence be an unauthorized disposition of China’s maritime rights and shall be null and void, create no obligations for China, and cannot alter the lawful status of China’s maritime entitlements.

II. Window of Opportunity and Quasi-Alliance Collusion

The timing chosen by Japan and the Philippines to high‑profile launch these “delimitation negotiations” reveals sinister political motives that warrant high vigilance.

This move is a speculative gambit amid the critical window of the Code of Conduct in the South China Sea (COC) negotiations. The year 2026 is a crucial stage for concluding the COC. The Philippines, as the rotating chair of ASEAN, while publicly pushing forward COC consultations, has secretly colluded with Japan in an attempt to create a fait accompli before the conclusion of the COC and gain an upper hand in the game.

It is also a typical example of Japan and the Philippines using maritime cooperation to strengthen their “quasi‑alliance” and support the US Indo‑Pacific Strategy. At the Japan‑Philippines summit in May 2026, the two sides formally launched negotiations on the General Security of Military Information Agreement (GSOMIA), upgraded their bilateral relationship to a “Comprehensive Strategic Partnership,” and stepped up defense and security integration, taking shape as a quasi‑alliance. This provides an important strategic fulcrum for the US Indo‑Pacific Strategy in the Western Pacific and Southeast Asia, and creates conditions for trilateral U.S.-Japan-Philippines coordination in relevant waters to contain and exert pressure on China.

III. The Grave Danger of Rising “Three‑Sea Linkage” Risks

By conniving across maritime areas, Japan and the Philippines have opened Pandora’s box of risk linkage between the East China Sea, the Taiwan Strait and the South China Sea, severely undermining China’s neighboring strategic security landscape.

First, these talks undermine the Taiwan question and the post‑war international order. Japan and the Philippines arbitrarily dispose of rights and interests in the waters surrounding China’s Taiwan Island, in essence challenging Taiwan’s status as part of China under international law and China’s sovereign rights and jurisdiction over the adjacent waters. This provides a pretext for “Taiwan independence” separatist forces to collude with external forces, heightens tensions and turbulence in the Taiwan Strait, and seriously disrupts the peaceful development of cross‑strait relations.

Second, Japan and the Philippines seek self‑interests at the expense of others, severely undermining peace and stability in the adjacent waters. The two sides serve their own interests and seek to grab maritime and geopolitical gains by relying on the US Indo‑Pacific Strategy. Japan takes the opportunity to break free from post‑war military constraints and accelerate overseas military expansion; the Philippines, relying on U.S. and Japanese support, attempts to illegally seize maritime interests. Such moves are likely to be emulated by other regional countries and threaten maritime order and stability.

Third, these actions serve major‑power geopolitical rivalry and fuel regional bloc confrontation. The Japan‑Philippines moves serve the U.S. geopolitical layout in the Asia‑Pacific. Through enhanced Japan‑Philippines defense and maritime cooperation, the United States steps up its interference in maritime affairs in the Western Pacific, consolidates the U.S.-Japan-Philippines trilateral security cooperation framework, stokes confrontation and sows discord in the region, and seriously hinders regional multilateral cooperation.

Conclusion: China Stands Firm and Resolutely Safeguards Its Maritime Rights and Interests

The Japan‑Philippines political scheme packaged as “maritime delimitation” seriously violates international law, harms China’s interests and undermines regional stability. China’s position is clear and firm: China has indisputable sovereignty over Taiwan Island and sovereign rights and jurisdiction over its adjacent waters. China’s legitimate maritime rights and interests shall not be affected by any bilateral arrangements between other countries. China will resolutely safeguard its maritime rights and interests through political, diplomatic and legal means, and uphold peace, stability and maritime order in the Asia‑Pacific. Any attempt to infringe upon China’s maritime rights and interests through bilateral negotiations is doomed to fail.

(Author: Zhang Qiyue, Assistant Director and Research Fellow, Institute for Global Governance, Shanghai Institutes for International Studies)