Philippines' Foreign Minister Maria Theresa Lazaro delivers a speech at the Nikkei Forum at a hotel in Tokyo on June 10, 2026. Photo: VCG

In response to the Philippine foreign minister's claim that its boundary discussions with Japan "have nothing to do" with China, a Chinese expert on Thursday said the so‑called Japan-Philippines maritime delimitation talks concern an area east of China's Taiwan island and contradict international law and the United Nations Convention on the Law of the Sea. The expert noted the move carries ulterior purposes beyond bilateral discussions.

Philippine Secretary of Foreign Affairs Maria Theresa Lazaro said that establishing clear maritime boundaries between the Philippines and Japan is of vital importance to the country's national defense in an interview on Wednesday.

China has criticized such negotiations, while Lazaro claimed the discussion "has nothing to do with them" and "just between the Philippines and Japan." She added, "We should continue with our delimitation talks," even if China keeps objecting or increases pressure, Nikkei Asia reported.

Lazaro also expressed so-called concern over increasing activities by Chinese vessels in waters close to the Taiwan island, per the outlet. 

Ding Duo, Director of the Research Center for International and Regional Issues at the National Institute for South China Sea Studies, told the Global Times on Thursday that Lazaro's words constitute three violations.

First, it violated the international law, in particular the Vienna Convention on the Law of Treaties, which stipulated, in simple words, that "bilateral treaty does not create obligations or rights for a third State." If the Philippines and Japan reach any agreement regardless of China interests, that constitute a violation, Ding said. 

Second, such discussions ran counter to the United Nations Convention on the Law of the Sea, which stipulated equity in maritime boundary delimitation. Based on this principle, given that the delimitation involves China's interests, and the final decision must not bypass China, Ding added.

The expert further noted that third, in a situation that three parties interests are involved, the acts of Philippines and Japan violated the "obligation of restraint" and "principle of good faith" in international law. 

Japan and the Philippines have been hyping so-called maritime delimitation issue recently, concerning an area east of China's Taiwan island. Japanese Prime Minister Sanae Takaichi and Philippine President Ferdinand Marcos Jr. agreed to start formal talks on EEZ boundaries and the continental shelf when the president visited Tokyo on a state visit in May, per reports. 

In response, Chinese Foreign Ministry spokesperson Mao Ning said on May 29 that according to China's domestic law and international law including UNCLOS, China has exclusive economic zone and continental shelf in this area. Japan and the Philippines' so-called maritime delimitation talks constitute a severe violation of China's maritime rights and interests, UNCLOS and other international law and basic norms governing international relations. China strongly deplores and firmly opposes that and has lodged serious protests with both countries.

The so-called delimitation talks are completely illegal, null and void, and will have no effect on China's claims to rights in the area east of the Taiwan island or exercise of China's lawful rights. China urges Japan and the Philippines to immediately stop any violation of China's maritime rights and interests and take concrete actions to uphold regional peace and stability.

Ding also noted that in addition to diplomatic methods to break the Japan-Philippines collusion, China can also conduct normal maritime law enforcement, patrols and drills to demonstrate its legitimate rights. These are all granted by the international law and can be routinized, he said. 

The expert also warned that the collusion between Japan and Philippines aims beyond "delimitation," but serves as stepping stone to squeeze China's maritime operational space in the waters east of the Taiwan Island. 

After so-called delimitation, they could scheme to carry out security cooperation, military collaboration and naval exercises, confining China's maritime activities in this area, Ding elaborated. 

"Such geostrategic moves are disguised under the pretext of legal frameworks and maritime delimitation. And they may also blend in "Taiwan independence" agenda in this process," Ding warned. 

The negative impact of their collusion could go further, analysts said, citing the two countries' deepening military cooperation. 

"The defense cooperation with Japan is one of the most important vital elements that we have in the Philippines, both nationally and for regional peace and security," Lazaro  said, according to Nikkei Asia.

The two nations agreed last month to deepen their cooperation, with Japan considering to export defense equipment to the Philippines. "This is part of the modernization process and towards the peace and security in the free Indo-Pacific," Lazaro said.

The so-called cooperation between Japan and the Philippines cater to both countries' respective ambitions and carries strong Cold War undertones, analysts said, warning against Japan's dangerous neo-militarist resurgence and Philippines' adventurist tendency.