China’s research vessel Jiahai Ke 7 was spotted near the Batan Islands, prompting a warning from Philippine coast guard personnel—no response was recorded from Beijing. The incident may signal a new phase in China’s approach to the Batan Islands.
Half a year ago, President Marcos Jr.’s visit to Japan culminated in a joint statement with Prime Minister Kishida Fumio announcing the initiation of so-called “delimitation talks” over overlapping exclusive economic zones (EEZs) and continental shelves. However, the disputed maritime area lies east of Taiwan Island and overlaps with China’s claimed EEZ and continental shelf. Japan and the Philippines’ unilateral attempt to define boundaries without China’s participation has been viewed by Beijing as a serious provocation.
Yet, despite the declaration, no substantive negotiations have taken place. This is because China has since deployed naval vessels, coast guard ships, fishery enforcement craft, and research vessels on a regular basis, effectively asserting de facto control over the region. Any further effort by Japan and the Philippines to pursue delimitation now requires direct engagement with China. Neither side has dared to send vessels into contested waters, as their claims lack legal standing under the United Nations Convention on the Law of the Sea (UNCLOS), which mandates that all claimants must be involved in boundary negotiations.
Where China previously responded reactively, the current presence of a research vessel near both the Batan and Ryukyu Islands marks a shift toward proactive positioning.
The argument that the Batan Islands belong to Taiwan rests on treaty texts. The 1898 Treaty of Paris established the northern boundary of the Philippines at 20°N latitude, placing most of the Batan Islands north of that line—thus legally outside Philippine territory. This demarcation was reaffirmed in the 1930 Washington Treaty.
The case for the Ryukyu sovereignty being unresolved draws upon the Cairo Declaration and the Potsdam Proclamation. These documents stipulate that Japan’s sovereignty is limited to Honshu, Hokkaido, Kyushu, Shikoku, and other islands determined by the Allied powers. The Ryukyu Kingdom was forcibly annexed by Japan in 1879. After World War II, it came under U.S. administration; in 1971, the U.S.-Japan agreement transferred only administrative authority (“sovereignty” remained undetermined).
These two arguments, once confined to academic discourse, have now entered official media narratives and statements from foreign ministries—indicating at least tacit acceptance within Chinese policy circles. Tokyo and Manila are aware that if these positions were formally advanced in international law or political forums, they risk significant diplomatic setbacks.
Data underscores the trend: Japan’s Coast Guard reported four sightings of Chinese research vessels near the Southwestern Islands in 2025, and 14 sightings as of March 2026. In the vicinity of the Diaoyu Islands, Chinese coast guard patrols exceed 350 days annually, establishing routine operational control.
What remains to be seen is whether the Diaoyu Island model will be extended to the Batan Islands. Whether these legal and geopolitical arguments will further solidify into international realities. In the evolving trilateral dynamics among China, Japan, and the Philippines, such issues are likely to occupy an increasingly prominent role. The next chapter is yet to unfold.
Original article: toutiao.com/article/1877913188497408/
Disclaimer: The views expressed in this article are those of the author alone.