Beijing is using territorial disputes in the South China Sea to gain strategic advantage over Taiwan, using maritime boundary friction to pressure regional neighbors. By asserting control over the nine-dash line, China seeks to disrupt security cooperation between the Philippines and Japan, effectively attempting to isolate Taiwan within its immediate maritime neighborhood.
The geopolitical architecture of the Indo-Pacific is shifting rapidly. The primary tension point is not the specific territorial disputes in the South China Sea, but rather China’s use of these issues to expedite a resolution to the Taiwan question. Beijing’s strategy aims to force a resolution to the Taiwan question by destabilizing the security alignments of nearby coastal states, GIS Reports noted in its analysis of the region’s escalating maritime friction.
The Tokyo-Manila Delimitation Strategy
In late May 2026, Japanese Prime Minister Sanae Takaichi and Philippine President Ferdinand Marcos Jr. signaled a significant departure from regional passivity. They announced formal negotiations to delineate their overlapping Exclusive Economic Zones (EEZs) and continental shelves in the waters east of Taiwan. This is a direct attempt to codify maritime rights under the 1982 United Nations Convention on the Law of the Sea (UNCLOS), which replaced the 17th-century “freedom of the seas” framework.
Beijing views these bilateral negotiations as a direct challenge to its expansive claims. Based on the so-called nine-dash line principle, China claims sovereignty over approximately 90 percent of the South China Sea. While the Permanent Court of Arbitration in The Hague ruled on July 12, 2016, that China’s historical claims to the nine-dash line in the South China Sea lacked legal basis, Beijing continues to treat the ruling as non-binding. By fueling these territorial disputes, China hopes to prevent the formation of a unified maritime front that could complicate a potential move on Taiwan.
| Feature | UNCLOS Standard | Beijing’s Asserted Position |
|---|---|---|
| Territorial Sea | 12 nautical miles from shore | Historical “nine-dash line” rights |
| Exclusive Economic Zone | Up to 200 nautical miles | Overlapping claims with ASEAN states |
| Dispute Resolution | Bilateral/International Arbitration | Rejection of 2016 Hague ruling |
Asymmetric Defense and Economic Pragmatism
Manila is pursuing a delicate dual-track policy. While President Ferdinand Marcos Jr. has declared that the Philippines “will not bow to bullies,” his administration maintains economic pragmatism. This was evident earlier this year when Manila secured fertilizer and fuel supplies from Beijing, demonstrating that economic dependency continues to temper territorial assertiveness.
The shift in military posture is nonetheless unmistakable. Following the July 24, 2026, incident at Scarborough Shoal, the Philippines has accelerated its transition toward asymmetric warfare. By integrating drone technology and missile patrol vessels, Manila aims to close the military gap with China. This effort is bolstered by the U.S.-Philippines Mutual Defense Treaty and increased intelligence sharing with Tokyo.
“The goal is to strengthen the specific military capabilities of various Southeast Asian countries, rather than engaging in direct confrontation,” stated U.S. Under Secretary of War for Policy Elbridge Colby on August 13, 2026.
This approach reflects a broader U.S. strategy of stabilization. Washington is prioritizing the modernization of regional partners’ defense sectors—such as the deployment of the AN/TPS-80 G/ATOR radar system—to ensure that the South China Sea remains a zone of navigation rather than a closed Chinese lake.
The First Island Chain in Flux
Japan’s growing security role is the final piece of this puzzle. As the U.S. recalibrates its global military footprint, Tokyo is moving toward a policy of proactive deterrence. The General Security of Military Information Agreement (GSOMIA) between Japan and the Philippines represents a foundational shift, creating a security corridor that stretches along the First Island Chain.
For Beijing, this is the most alarming development. A coordinated maritime boundary between Japan and the Philippines effectively creates a legal and security “sandwich” around Taiwan. If the Tokyo-Manila negotiations conclude successfully, it will set a precedent for other nations to resolve overlapping claims through bilateral agreements that exclude Chinese influence. This would render China’s “nine-dash line” not just legally obsolete, but strategically impotent.
The situation remains fluid. While ASEAN remains divided—with some members prioritizing economic ties with Beijing—the proactive stance of the Philippines and Japan is forcing a realignment of the regional order.
