Regional Turbulence and Cross-Strait Ties

Introduction

Japan and the Philippines announced they will begin negotiations to delimit their exclusive economic zones (EEZs) and continental shelves (essentially their maritime boundary).[i] The announcement, the latest in a series of adverse developments in China–Japan relations and in the South China Sea (SCS), has potential implications for the regional strategic-security landscape as well as cross-Strait ties.

The intended maritime area for the announced negotiations includes maritime territory near Japan’s southernmost islands, such as the Yaeyama Islands, and the Philippines’ northernmost islands, such as Mavulis Island. Importantly, this entire maritime area lies directly east of Taiwan.[ii] A proposed delimitation of the maritime boundary of EEZs and continental shelves in the region “significantly overlaps with Taiwan’s [claims]” and China sees the attempt as a challenge to its position on Taiwan.[iii]

China and Taiwan’s Stances on Proposed Negotiations

Taiwan is a self-governing territory that functions under the name of the Republic of China (ROC) and claims sovereignty. The People’s Republic of China (PRC, China), which is committed to “reunifying” Taiwan with the mainland, rejects this claim. Except for a few tiny nations, the international community does not recognise the ROC’s existence or Taiwan’s sovereign status. Therefore, its maritime claims under the United Nations Convention on the Law of the Sea (UNCLOS) and other relevant laws remain unenforceable.

From a strictly legal point of view, the Chinese claim that the area in question lies “east of China’s Taiwan Island” would be more congruent. However, until now, this has essentially remained a theoretical assertion of sovereignty due to Taiwan’s de facto separation from the mainland. China has chosen not to disturb the status quo on the islands, islets or atolls held by Taiwan—the Taiwanese administration exercises control over islands such as Kinmen, Matsu and Penghu in the Taiwan Strait, and Taiping Island (Itu Aba) in Nansha (Spratly) Islands and Dongsha (Pratas) Islands in the SCS.

Yet the proposition that China’s relaxed stance towards Taiwan-controlled islands, which are essentially indefensible from a military perspective, could change, especially amid intensified and aggressive strategic-security manoeuvres in the contested maritime regions of the SCS, East China Sea (ECS) and the western Pacific, should not be dismissed as improbable.

For its part, Taiwan has welcomed Japan and the Philippines “for working to resolve maritime differences through peaceful dialogue and based on respect for international law”.[iv] Reiterating its sovereignty over the relevant maritime area, it has urged them to take into account its interests, especially its pre-existing fishery agreements with the two countries, during negotiations.[v] However, China has denounced the announcement as violating its “domestic law and international law including UNCLOS” and “a severe violation of [its] maritime rights and interests”.[vi] It has maintained that these talks are detrimental to regional peace and stability.[vii]

Furthermore, criticising Taiwan’s stance, it has reiterated that upholding “national sovereignty and maritime rights and interests is the shared responsibility of all Chinese people on both sides of the Strait” and the current Taiwanese administration’s move “betrays ancestors and breaches all moral boundaries”.[viii] On its part, Taiwan has responded to Chinese castigations by saying that “China has no right to comment on the territory and appertaining waters of the Republic of China (Taiwan)”.[ix] It views China’s military power projection through the lens of “maritime law enforcement” as a regional peace and stability concern.[x]

China sent ships “to carry out a ‘special maritime traffic law-enforcement operation’ in the waters east of Taiwan in ⁠response to the Japanese and Philippine announcement”.[xi] On 6 June 2026, Taiwan reported that “a Chinese coast guard ship and a survey ship had carried out the first coordinated operation to ‘provoke’ ‌Taiwan, in waters around strategically located islands” in the SCS.[xii] The incident saw a rhetorical standoff between the two sides.[xiii] This seems to be a direct response to the present Taiwan administration’s stance on the proposed talks between Japan and the Philippines.

Regional Turbulence and Their Impact

Given the state of cross-Strait relations, which are at their lowest since rapprochement began in the early 1990s, getting sucked into the regional strategic turbulence is not beneficial for Taiwan. The proposed talks between Japan and the Philippines are in keeping with their increasing cooperation in view of the overall security situation vis-à-vis China that has developed in recent years. China–Japan relations have nosedived since Prime Minister Sanae Takaichi’s 7 November statement that a crisis in the Taiwan Strait could pose a potentially “survival-threatening situation” for Japan.[xiv] Her government’s revision of the Three Principles of Japan’s Arms Transfer has invited a strong Chinese reaction, which termed the revision as “remilitarisation” or “neo-militarism”, evoking historical fears of renewed Japanese aggression.[xv]

Recently, in April 2026, the Japanese naval destroyer JS Ikazuchi sailed through the Taiwan Strait as an expression of freedom of navigation, which China slammed as a “deliberate provocation”.[xvi] Besides, Japan has invested through its Official Security Assistance (OSA) in strengthening regional networks with countries such as the Philippines, Vietnam, and other Southeast Asian states, which share security concerns vis-à-vis China.

Japan appears to be showing a sense of urgency amid deepening uncertainty about President Trump’s US commitments to the security of allies and partners. Both China and Japan are accusing each other of stoking hyper-nationalism and xenophobia. China accuses Takaichi of indulging in hyper-nationalist right-wing politics targeting China. Japan is concerned about increasing physical attacks on Japanese nationals in China and Chinese citizens indulging in aggressive behaviour on Japanese soil.

Separately, the Philippine Defence Secretary Gilberto Teodoro at the Shangri-La Dialogue remarked that “the Philippines was collaborating with Taiwan in ‘non-taboo areas’ outside of diplomatic recognition”, including a Taiwan–Philippines economic corridor, which has “indirect but very important implications for [their] defence space”.[xvii] He noted that in addition to strengthening security ties with the US, his country was “seeking exchanges and cooperation with such defence partners as Japan, Vietnam, and Taiwan to respond to regional challenges jointly”.[xviii] These remarks were unusually explicit. Taiwan welcomed the remarks.[xix] China has criticised his speech at the dialogue and appealed to the Philippines government to “rein in” its officials.[xx]

Incidentally, the Philippines has become vocal on Taiwan, inviting Chinese backlash under President Ferdinand Marcos Jnr. On more than one occasion, he has said that the Philippines will be affected by a war in the Taiwan Strait. In his statement in May 2026 ahead of his visit to Japan, he underlined that geographical proximity and the presence of around 200,000 Filipino immigrants in Taiwan will naturally affect his country. This statement also drew China’s ire.[xxi]

Implications for Cross-Strait Relations

Thus, Taiwan getting sucked into regional strategic contestations around maritime disputes, independent of US–China competitive dynamics but driven by regional actors, is not an indistinct possibility. If security and strategic manoeuvres intensify and become more aggressive in the maritime region, China may reconsider its relaxed stance towards Taiwan-controlled islands. Until now, it has viewed the islands as its ‘Taiwan problem’. Its One China convictions have shaped this stance. The main reason it has not initiated any kinetic action to snatch the islands is that it does not want to send a wrong message about its commitment to the One China principle. If it is unable to subsequently “reunify” all of Taiwan due to US involvement or other obstacles, it would not want to inadvertently create the perception of the divisibility of Chinese territory.[xxii] In a changed situation, it may apply the One-China logic only to the Kinmen, Matsu and Penghu islands. These are populated islands located within the Taiwan Strait, and there is no dispute over them with any other country.

On the other hand, the islands, islets and atolls that Taiwan controls in the SCS are part of multi-state maritime disputes and are primarily uninhabited. In this context, China could have reason to assert itself as the defender of ‘Chinese territories and sovereignty’, a role that, in its view, the Taiwanese authorities are unable to fulfil. Therefore, it could withdraw the considerations it accords to Kinmen, Matsu and Penghu from these islands.

Conclusion

It is uncertain whether the Chinese use of force or coercion against Taiwan-held islands in the SCS would invite a regional response and trigger a wider regional conflict. Perhaps it would not lead to that. However, losing these maritime possessions would seriously damage Taiwan’s standing. Therefore, Taiwan must handle the situation carefully and prevent any such eventualities.

[i] “Press Conference by the Chief Cabinet Secretary (June 3, 2026 – Morning)”, Government of Japan.

[ii] Laura Zhou, “Why have Japan and the Philippines’ Maritime Boundary Talks Angered China?”, South China Morning Post, 2 June 2026.

[iii] Laura Zhou, “Are Japan-Philippines Talks a Maritime Red Line for China’s Blue-Water Ambitions?”, South China Morning Post, 4 June 2026.

[iv]  “MOFA Response to China’s Claims Concerning Japan-Philippines Negotiations on Maritime Boundary”, Ministry of Foreign Affairs, Republic of China (Taiwan), 31 May 2026.

[v] “MOFA Response to Japan-Philippines Maritime Boundary Delimitation Talks”, Ministry of Foreign Affairs, Republic of China (Taiwan), 3 June 2026.

[vi] “Foreign Ministry Spokesperson Mao Ning’s Regular Press Conference on May 29, 2026”, Ministry of Foreign Affairs, People’s Republic of China, 29 May 2026.

[vii] Ibid.

[viii] “Foreign Ministry Spokesperson Mao Ning’s Regular Press Conference on June 2, 2026”, Ministry of Foreign Affairs, People’s Republic of China, 2 June 2026.

[ix] “MOFA Response to China’s Claims Concerning Japan-Philippines Negotiations on Maritime Boundary”, no. 4.

[x] “MOFA Response to Japan-Philippines Maritime Boundary Delimitation Talks”, no. 5.

[xi] “China Launches Maritime Law Enforcement Operation in Waters East of Taiwan Island after Japan-Philippines Unilateral Delimitation Move”, Global Times, 6 June 2026; Ben Blanchard, “China Coast Guard Patrols ‘Provocative,’ MND Says”, Taipei Times, 9 June 2026.

[xii] Ben Blanchard, “Chinese Research Vessel Approaches Pratas Islands”, Taipei Times, 7 June 2026; Kelvin Chen, “Taiwan Deploys Larger Patrol ships to Dongsha Island”, Taiwan News, 1 June 2026.

[xiii] Ibid.

[xiv] Sayuri Romei, “Japan’s Takaichi Stands Firm on Taiwan”, German Marshal Fund, 4 December 2025.

[xv] “Spokesperson: China Concerned about Japan’s Plan to Revise ‘Three Principles on Transfer of Defense Equipment and Technology’”, The State Council Information Office of PRC, 7 April 2026.

[xvi] “Chinese Defense Spokesperson Blasts Japanese Destroyer Transiting Taiwan Strait”, Ministry of National Defence of PRC, 17 April 2026.

[xvii] Keoni Everington, “Philippines Eyes Closer Taiwan Ties to Bolster Deterrence Against China”, Taiwan News, 1 June 2026.

[xviii] “MOFA Welcomes Public Comments from Philippine Secretary of National Defense Teodoro on Deepening Taiwan-Philippines Cooperation”, Ministry of Foreign Affairs, Republic of China (Taiwan), 1 June 2026.

[xix] Ibid.

[xx] “China Urges Philippines to Rein in Officials over Defense Chief’s Remarks”, CGTN, 3 June 2026.

[xxi] Phoebe Zhang, “Beijing Rebukes Philippines over Claim Proximity Guarantees Involvement in Taiwan Conflict”, South China Morning Post, 19 May 2026.

[xxii] Prashant Kumar Singh, “How Vulnerable are Kinmen and Matsu Islands?”, Special Feature, Manohar Parrikar Institute for Defence Studies and Analyses (MP-IDSA), 23 June 2025.