By Focus | 2026-07-27

China has escalated its legal opposition to planned maritime boundary negotiations between Japan and the Philippines by conducting sustained coast guard operations east of Taiwan. The Chinese campaign against the talks has no basis in international law, legal analysts say.

Japan and the Philippines announced May 28 that they would begin formal negotiations to delimit the boundary of their Exclusive Economic Zones and continental shelf under the United Nations Convention on the Law of the Sea (UNCLOS). China, which claims sovereignty over Taiwan and surrounding waters, was not a party to the talks.

Beijing says the proposed boundary overlaps maritime zones it claims through its assertions over Taiwan and surrounding waters. It says Japan and the Philippines should not proceed without China's participation. The dispute has become a test of whether neighboring coastal states may negotiate maritime boundaries under UNCLOS without outside participation, or whether China may establish a broader role in such talks.

Legal challenge

Within days of the announcement, China's Ministry of National Defense called the negotiations "completely illegal and null," saying they infringed on China's maritime rights. After weeks of coast guard patrols and maritime law enforcement operations east of Taiwan, Beijing on July 2 published a legal opinion through the Ministry of Natural Resources' China Institute for Marine Affairs (CIMA). It asserted that Japan and the Philippines had violated international law by launching delimitation talks without consulting China.

UNCLOS provides no basis for China's argument because it allows neighboring coastal states to negotiate maritime boundaries between themselves without third-party consent, say legal scholars.

UNCLOS makes clear that maritime entitlements are generated by a state's own coastline. Accordingly, the Japan-Philippines negotiations are a routine exercise of coastal state rights, observers say. Any eventual agreement would bind only the two parties and would not diminish the lawful rights of non-parties, including freedom of navigation, overflight and other lawful uses of the sea.

UNCLOS does not require every potentially interested party to participate in the same negotiation, said James Kraska, an international maritime law scholar at the U.S. Naval War College. Two-country maritime agreements routinely specify they are without prejudice to the rights of third parties, he said.

A Taipei Times editorial likewise noted that UNCLOS delimitation talks between two coastal states require no third-party consent and that any resulting agreement would have "no legal nexus" with a state that is not party to it. Taiwan would remain entitled to its own 200-nautical-mile maritime zone regardless of the negotiations, while existing fishery agreements with Japan and the Philippines already protect Taipei's interests, it said.

Pressure at sea

China's legal challenge has been accompanied by a growing coast guard and maritime law enforcement presence east of Taiwan, a combination analysts say reflects Beijing's broader use of "lawfare" -- employing legalistic ruses alongside sustained operational pressure to reinforce its maritime claims without resorting to armed conflict.

China's objection reflects a broader effort to transform a routine country-to-country legal process into support for its own jurisdictional claims, Jing Ge, an instructor at Florida International University, wrote in an analysis published by the Lowy Institute. She said Beijing was using a "sovereignty narrative" to recast a two-country maritime delimitation process as justification for expanding its own administrative and jurisdictional claims.

Beginning June 1, two China Coast Guard (CCG) cutters patrolled waters east of Taiwan in what Beijing described as a response to the Japan-Philippines negotiations. CCG spokesman Jiang Lue called the deployment "a necessary action" to safeguard China's maritime rights.

China's Ministry of Transport followed up with a five-day, multi-agency "special maritime traffic law enforcement operation" from June 6 to 10. The operation inspected 198 vessels, took "corrective" action against three and patrolled undersea cable routes east of Taiwan, in what Focus previously reported as an unprecedented expansion of Chinese law enforcement activity in the area.

China's Maritime Safety Administration followed with a four-ship "special maritime traffic law enforcement operation" from June 6 to 10, circumnavigating Taiwan alongside separate Chinese survey vessels. The size, location and activities of the operation amounted to an unprecedented, unilateral change to the status quo.

The patrols marked a shift in Beijing's enforcement presence toward waters closer to Taiwan's main island and farther into the Pacific to its east, Tang Ming-hui, a researcher at the ASEAN Economic, Trade and Culture Development Association, wrote in a commentary published by Mirror Media.

Beijing published the CIMA legal opinion on July 2, offering its most detailed legal justification for opposing the negotiations while CCG vessels continued operating east of Taiwan.

CCG and Japanese coast guard vessels confronted one another near the Senkaku Islands on July 7. Separately, China's military deployed bombers, fighter aircraft and naval vessels around Scarborough Shoal in the South China Sea, moves analysts described as part of Beijing's broader response to the Japan-Philippines talks.

Allies push back

The United States, Britain, France and Germany have dismissed China's efforts to challenge the talks.

A U.S. State Department spokesperson rejected "any assertion by China of authority to interfere with freedoms of navigation or overflight, the freedom to lay cables, or other lawful uses of the sea."

Britain, France and Germany said on June 24 that China's maritime activities "threaten regional stability and the freedom of navigation and safety of international shipping," reiterating opposition to "any unilateral change to the status quo" through force or coercion.

Taiwanese President Lai Ching-te likewise said the planned negotiations could not affect a third country's rights under the Vienna Convention on the Law of Treaties and said China had no legal claim to the waters because it is not geographically adjacent to the area under negotiation. Taiwan's fishery agreements with Japan and the Philippines would remain unaffected regardless of the talks' outcome, he said.

Japan and the Philippines have continued to describe the negotiations as a routine country-to-country process conducted under international law. Analysts say the dispute extends beyond a single maritime boundary, testing whether neighboring coastal states can resolve overlapping claims through UNCLOS without outside vetoes or political pressure.