A television screen shows a news report on patrol and law‑enforcement operations around Taiwan conducted by the China Coast Guard, at a restaurant in Beijing in late December. | REUTERS
From JapanTimes by Gabriel Dominguez
At first glance, Japan and the Philippines’ decision to begin negotiations on a maritime boundary appears to be a routine exercise in international law. But China’s unusually forceful response signals that the talks are about far more than drawing a line at sea.
Beijing argues the talks infringe on maritime rights it claims through Taiwan and sees discussions as part of a broader effort by two key U.S. allies to deepen strategic coordination in waters central to China’s security interests.
When Prime Minister Sanae Takaichi and Philippine President Ferdinand Marcos Jr. used a late-May summit in Tokyo to launch the bilateral delimitation talks, China reacted swiftly.
China not only declared the negotiations “illegal, null and void” and lodged diplomatic protests, but also backed its rhetoric with action, deploying coast guard vessels for what it described as “law-enforcement patrols” east of Taiwan, which Beijing claims as its own territory.
By extending its operations south of Yonaguni Island into waters Tokyo considers part of its exclusive economic zone (EEZ), Beijing underscored its determination to contest the talks both diplomatically and at sea.
Under the United Nations Convention on the Law of the Sea (UNCLOS), such negotiations are routine whenever states have overlapping EEZs and continental shelves.
EEZ with the GeoGarage platform
More than routine talks
So why has Beijing reacted so strongly?
The answer lies in the unique geography of the waters east of Taiwan, where international law, the self-ruled island’s contested status and intensifying strategic competition converge.
What would otherwise be a routine delimitation has become a contest over how one of the Indo-Pacific’s most sensitive maritime corridors should be governed.
A China Coast Guard vessel sails near a Japan Coast Guard vessel around the Japanese-controlled Senkaku Islands last September. | HITOSHI NAKAMA / VIA REUTERS
Japan and the Philippines do not share a land border, but their EEZs and continental shelves overlap because Japan’s southwestern islands and the Philippines’ northernmost islands lie less than 400 nautical miles (740 kilometers) apart.
Taiwan, meanwhile, sits almost directly between Japan and the Philippines.
Any eventual boundary would almost certainly pass through waters where maritime entitlements generated by the island overlap with those claimed by Tokyo and Manila.
Because Beijing considers those entitlements as belonging to China, the negotiations inevitably intersect with the Taiwan issue, transforming an otherwise routine legal exercise into one with significant strategic and political implications.
Because Beijing considers those entitlements as belonging to China, the negotiations inevitably intersect with the Taiwan issue, transforming an otherwise routine legal exercise into one with significant strategic and political implications.
Why Beijing is so alarmed
China argues that Taiwan is an inalienable part of its territory and that the maritime rights generated by the democratic island therefore fall under Beijing’s jurisdiction.
From that perspective, any boundary negotiated in these waters cannot legitimately proceed without China’s participation.
Japan and the Philippines reject that premise. While both acknowledge Beijing’s “One China” position, neither recognizes Chinese sovereignty over Taiwan.
By negotiating under UNCLOS, they are treating the issue as a bilateral maritime delimitation rather than one requiring China’s participation.
Japan and the Philippines reject that premise. While both acknowledge Beijing’s “One China” position, neither recognizes Chinese sovereignty over Taiwan.
By negotiating under UNCLOS, they are treating the issue as a bilateral maritime delimitation rather than one requiring China’s participation.
That framework does not require every potentially interested party to participate in the same negotiation, and such agreements routinely state that they are without prejudice to third-party rights.
If concluded, a boundary deal would reinforce a framework for managing overlapping maritime claims while leaving third-party rights formally unresolved.
The talks are designed to “cement Japan-Philippine maritime cooperation” by clarifying the boundary and facilitating closer political, military and economic ties, said James Kraska, an expert on international maritime law at the U.S. Naval War College.
If concluded, a boundary deal would reinforce a framework for managing overlapping maritime claims while leaving third-party rights formally unresolved.
The talks are designed to “cement Japan-Philippine maritime cooperation” by clarifying the boundary and facilitating closer political, military and economic ties, said James Kraska, an expert on international maritime law at the U.S. Naval War College.
Why now?
Japan and the Philippines have claimed overlapping maritime zones for decades, yet neither prioritized boundary talks until recently.
What has changed is the regional security environment.
A China Coast Guard ship is seen on the horizon through a telescopic view from Philippine-occupied Thitu Island in the disputed South China Sea in February. | REUTERS
China’s sustained maritime pressure — including expansive South China Sea claims, growing coast guard operations around disputed features and repeated incursions into waters surrounding the Japanese-controlled but Chinese-claimed Senkaku Islands — has led Tokyo and Manila to deepen defense ties at an accelerated pace.
Once centered on development assistance, the Japan-Philippine relationship has evolved into a comprehensive security partnership encompassing a visiting-forces agreement, defense equipment exports, closer military and coast guard cooperation and negotiations toward an expanded intelligence-sharing pact.
In that context, maritime delimitation has become another pillar of the rapidly expanding security partnership rather than merely a legal exercise. Clarifying the maritime boundary between the quasi-allies, Kraska said, removes lingering uncertainty and facilitates closer cooperation across political, military and economic domains.
‘First island chain’ legal geography
A maritime boundary agreement would establish a clearer legal framework in the strategically important waters linking the East China Sea, the Taiwan Strait and the South China Sea.
Far from simply drawing a line at sea, such a deal would contribute to the gradual alignment of the region’s legal geography with its evolving security architecture along the “first island chain” — the string of islands stretching from Japan toward Borneo.
By clarifying jurisdiction over fisheries, law enforcement and coast guard operations, a final agreement could complement allied coordination and maritime domain awareness in one of the Indo-Pacific’s most sensitive maritime corridors.
The strategic importance of these waters has grown as the Chinese Navy pushes farther into the western Pacific. Unlike the shallow and congested Taiwan Strait, the deeper waters of the Philippine Sea provide the Chinese Navy with a key route into the wider Pacific.
Defense analysts have long regarded this maritime space as critical to Beijing’s naval operations beyond the first island chain, which is also why strengthening coordination across the same corridor has become an increasingly important objective for Tokyo, Washington and Manila.
From diplomacy to ‘gray-zone’ competition
China’s response suggests it intends to contest not only the eventual outcome of the negotiations but also the premise that Japan and the Philippines can negotiate over those waters without Beijing.
The recent coast guard deployment suggests Beijing is increasingly willing to extend its “gray-zone” activities east of Taiwan, reinforcing its claims through regular deployments while contesting actions it believes undermine them.
A Taiwan Coast Guard ship patrols near Dadan Island, with China's Xiamen city visible in the background, last October. | REUTERS
Kraska suggests that China’s opposition ultimately reflects a broader objective: resisting developments that bring Japan and the Philippines closer together strategically. Viewed in that light, Beijing’s reaction is directed not only at the legal implications of a maritime boundary but also at what a deal would represent for the evolving regional balance.
Taiwan’s delicate balancing act
The negotiations also present a dilemma for Taiwan.
Taipei has generally welcomed closer security cooperation among Japan, the Philippines and other like-minded partners in response to growing Chinese military pressure.
At the same time, the island maintains its own longstanding maritime claims in the waters east of Taiwan. Openly endorsing a Japan-Philippines boundary could be interpreted as weakening those claims, while objecting to the negotiations would risk undermining cooperation with two of its most important partners.
Instead, Taiwan has adopted a dual-track approach. While rejecting Beijing’s claims and supporting closer cooperation with regional partners, its Foreign Ministry has also sought assurances through its representative offices in Tokyo and Manila that any eventual agreement would not prejudice Taiwan’s maritime rights or existing fisheries arrangements.
A parallel transformation
Much attention has focused on the military dimension of allied cooperation along the first island chain — from missile deployments and expanded access agreements to integrated operational planning and sophisticated joint exercises.
Less noticed is the parallel construction of a legal and institutional architecture driven by coast guard cooperation, reciprocal access agreements, intelligence sharing and maritime boundary negotiations.
While these initiatives do not resolve competing maritime claims or the complex legal questions surrounding Taiwan, they demonstrate how institutional cooperation has become a critical feature of the region’s security landscape.
The unfolding negotiations reveal that competition along the first island chain is no longer just about missile deployments and military exercises; it is increasingly a contest over the legal and institutional order governing these strategically important waters.
For years, Beijing has relied on sustained coast guard deployments and other gray-zone activities to reinforce its maritime claims. Japan and the Philippines, by contrast, are seeking to clarify jurisdiction and deepen bilateral cooperation through maritime delimitation and other institutional mechanisms.
As the negotiations progress, the waters east of Taiwan are becoming a testing ground for two competing approaches to managing the regional maritime order: one grounded primarily in sustained operational presence, the other in legal and institutional coordination.
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