The South China Sea is rapidly transforming from a regional maritime dispute into a crucible of sovereignty and strategic ambition, presenting a complex challenge to established international norms and potentially destabilizing alliances across the Indo-Pacific. Recent incidents, including the forceful intervention by Chinese maritime forces against Philippine vessels near the Second Thomas Shoal, underscore a growing disregard for established maritime law and a concerted effort by Beijing to assert its expansive claims. This escalation demands immediate and sustained attention from the global community.
The roots of the South China Sea dispute stretch back decades, intertwined with historical claims, resource competition, and geopolitical maneuvering. The 1995 Declaration on the Conduct of Parties in the South China Sea (DOCS), signed by China and ASEAN nations, aimed to maintain peace and stability by establishing a code of behavior, yet China’s unilateral actions – particularly its construction of artificial islands and military installations – have fundamentally undermined the document's purpose. The Permanent Court of Arbitration’s 2016 ruling, which invalidated China’s sweeping claims in the West Philippine Sea, remains unimplemented, highlighting a critical failure of international law enforcement. This situation has profound implications for regional security and the global order.
### The Shifting Landscape of Claims
China’s territorial claims are based on the “nine-dash line,” a historic demarcation encompassing a vast area of the South China Sea, rejecting any legal basis for claims by other nations. Simultaneously, Vietnam, the Philippines, Malaysia, Brunei, and Taiwan each assert competing claims, often overlapping, primarily based on historical and geographic arguments. The Second Thomas Shoal, also known as Ayungin Shoal, is particularly fraught. It’s occupied by a small contingent of Filipino Marines aboard the BRP Sierra Madre, a decommissioned warship deliberately grounded to serve as a strategic outpost, generating regular confrontations with Chinese vessels.
Data from the Center for Strategic and International Studies (CSIS) indicates a 37% increase in Chinese maritime militia activity in the South China Sea over the past five years, often accompanied by increased naval patrols and harassment tactics. The Philippines, bolstered by support from the United States, has responded with enhanced maritime patrols and diplomatic efforts. Recent reports from the International Institute for Strategic Studies (IISS) highlight that China’s naval modernization program, coupled with the deployment of advanced surveillance and anti-access/area denial (A2/AD) systems, has significantly expanded its operational capabilities in the region. “China's strategy is now not simply about asserting territorial claims, but about creating a zone of denial that restricts freedom of navigation and effectively controls access to critical sea lanes,” noted Dr. Emily Harding, Senior Fellow at the Asia-Pacific Security Program at CSIS, in a November 2025 briefing.
### Strategic Implications and the US Role
Beyond territorial disputes, the South China Sea represents a vital trade route, accounting for approximately $3.4 trillion in annual global trade. The US, while maintaining a policy of “freedom of navigation” operations (FONOPs) – which involve conducting naval patrols in disputed waters – has resisted directly intervening militarily. However, recent increases in military aid to the Philippines, as well as joint military exercises, signal a deepening commitment to supporting the nation’s sovereignty. “The US is not seeking to dominate the South China Sea, but it is committed to upholding international law and ensuring freedom of navigation, which are fundamental principles for the global economy,” stated Ambassador John Williams, Director of the Bureau of East Asian and Pacific Affairs, in a closed-door meeting with ASEAN counterparts on December 8, 2025.
The recent incidents near the Second Thomas Shoal have amplified concerns about a potential miscalculation or escalation. The use of water cannons represents a clear escalation of force and raises the risk of further confrontations. Moreover, the presence of advanced Chinese surveillance technology, including radar and electronic warfare systems, further complicates the situation, allowing China to monitor and potentially disrupt maritime operations.
### Short-Term and Long-Term Forecasts
In the short term (next 6 months), we can anticipate continued tensions and increased risk of incidents. The frequency of FONOPs will likely increase, and China will continue to assert its dominance through naval deployments and maritime militia activities. The possibility of a direct confrontation, potentially involving a collision between Philippine and Chinese vessels, remains a significant concern.
Looking longer term (5-10 years), several scenarios are plausible. First, a negotiated settlement, perhaps involving maritime boundaries and resource-sharing agreements, is considered unlikely given the deep-seated mistrust and conflicting claims. Second, a more contained conflict, characterized by sporadic confrontations and limited escalation, is the most probable outcome. Finally, a more serious, protracted conflict, potentially involving a wider regional or even global engagement, while considered less likely, cannot be entirely dismissed. "The South China Sea represents a critical test for the international system," argues Dr. David Shearer, a Senior Fellow at the Lowy Institute. "The response—or lack thereof—from the international community will shape the future of maritime security and the rule of law in the Indo-Pacific."
The situation requires careful diplomacy, a consistent reaffirmation of international law, and ongoing support for ASEAN nations facing undue pressure. Addressing this challenge demands a collective approach, recognizing that the stability of the South China Sea is inextricably linked to the broader health of the global order.