U.S.-China Military Confrontation in the South

📡 The Signal — What Happened

Why it matters: Since early 2026, an unprecedented situation has persisted in the South China Sea, with simultaneous military exercises by both the US and China. The risk of accidental armed conflict has reached its highest level since the end of the Cold War. This tension is not merely a bilateral dispute but a structural crisis that threatens the security order across the Indo-Pacific and the foundations of the global economy.

• Military Trends — From January to March 2026, the US Navy conducted "Freedom of Navigation" operations in the South China Sea at their highest frequency in the past five years, exceeding three times per month.
• Military Trends — In February 2026, the Chinese People's Liberation Army conducted large-scale live-fire exercises around the Spratly and Paracel Islands, expanding the exercise area beyond previous limits.
• Alliance Relations — In March 2026, the United States commenced "Balikatan Plus," a quadrilateral joint maritime exercise with the Philippines, Japan, and Australia, in the South China Sea.
• Territorial Claims — In February 2026, China announced the establishment of new administrative divisions in the South China Sea, signaling its intent to further strengthen jurisdiction within the nine-dash line.
• Diplomacy — At the ASEAN Foreign Ministers' Meeting (February 2026), negotiations for a Code of Conduct (COC) in the South China Sea effectively stalled, and the word "urgency" was removed from the joint statement.
• Economy — The annual trade volume passing through the South China Sea reaches approximately $5.3 trillion, with about one-third of global maritime trade relying on this waterway.
• Military Technology — Satellite imagery confirmed in early 2026 that China had completed the deployment of HQ-9B anti-aircraft missile systems and YJ-62 anti-ship cruise missiles on its artificial islands in the Spratly Islands.
• Domestic Politics — 2026 is a US midterm election year, and the Biden administration (or its successor) faces increasing domestic political pressure to demonstrate a tough stance against China.
• Legal Framework — The 2016 Permanent Court of Arbitration ruling (rejecting China's nine-dash line claim) continues to be ignored by China, indicating a dysfunctional international legal framework for resolution.
• Military Incidents — Since late 2025, at least 12 "dangerous close-encounter" incidents between US and Chinese military aircraft and vessels have been reported, already surpassing the total for 2024.
• Communication Channels — The US-China military hotline (crisis management communication channel), though reactivated in 2023, remains at a low operational level, raising concerns about its readiness in emergencies.
• Resources — The South China Sea is estimated to hold 11 billion barrels of oil and 190 trillion cubic feet of natural gas, with resource competition also driving tensions.

The military standoff between the US and China in the South China Sea did not suddenly begin in 2026. Its roots lie at the confluence of at least four historical trends.

First, there is the long-term evolution of China's maritime expansion strategy. The shift from Deng Xiaoping's "hide one's capabilities and bide one's time" (韜光養晦) approach to the construction of a "maritime power" (海洋強国) under Xi Jinping accelerated rapidly after 2012. From 2013 to 2015, seven artificial islands were built in the Spratly Islands, with runways, radar facilities, and missile positions successively installed. This was a classic example of the "salami-slicing" strategy, where each individual action did not reach the threshold for military conflict, but cumulatively fundamentally altered the status quo. Despite the 2016 Permanent Court of Arbitration ruling rejecting China's historical rights based on the nine-dash line, China dismissed it as "a piece of paper" and accelerated militarization.

Second, there is the reorganization of the US Indo-Pacific strategy. Starting with the Obama administration's "pivot to Asia," followed by the Trump administration's "Free and Open Indo-Pacific" concept in its first term, and the Biden administration's creation of AUKUS and institutionalization of the Quad, the US has positioned China's maritime expansion as a challenge to the existing international order and has progressively strengthened its military presence. Particularly since 2023, the military effectiveness of the alliance network has dramatically increased, including securing access to new bases in the Philippines under the Enhanced Defense Cooperation Agreement (EDCA) between the US and the Philippines, Japan's increase in defense spending to 2% of GDP, and the transfer of nuclear submarine technology to Australia.

Third, there is a shift in the position of regional countries. Under the Marcos Jr. administration, the Philippines adopted a tougher stance against China, leading to normalized physical confrontations with the China Coast Guard over Second Thomas Shoal and Scarborough Shoal. From 2024 to 2025, incidents such as water cannon attacks and laser illuminations frequently occurred between the Philippine military and the China Coast Guard, steadily climbing the ladder of escalation. Vietnam has also quietly proceeded with strengthening its occupied outposts in the Spratly Islands, and Indonesia has bolstered its defense capabilities around the Natuna Islands. The "balance of engagement and deterrence" towards China that ASEAN once maintained has largely collapsed, and a shared perception of the Chinese threat has emerged within the region.

Fourth, and most fundamentally, there is a structural change in US-China relations. The "liberal optimism" that economic interdependence would bring stability has completely collapsed after a series of trade wars, technological decoupling, and semiconductor export controls. Both countries are now in a phase of "comprehensive strategic competition" across all dimensions—economic, technological, military, and ideological—with a "chain of conflicts" structure where confrontation in one area spills over into others. The South China Sea is the most combustible contact point in this structural competition, and both sides are caught in a "commitment trap" from which they cannot retreat.

There are three direct factors contributing to the particularly high risk in 2026. First, it is a US midterm election year, creating a political environment where both ruling and opposition parties compete to demonstrate a tough stance against China. Second, a period has begun within the Chinese Communist Party where Xi Jinping's achievements in his third term are being scrutinized, and any perceived "weakness" externally could shake his power base. Third, there is a structural flaw where mechanisms for managing the risk of accidental clashes have not kept pace with the increasing frequency and scale of military exercises. Although a US-China military hotline exists, trust-building at the operational level remains insufficient since its reactivation in 2023, making the risk of miscommunication leading to an explosive situation extremely high.

The delta: The qualitative change that occurred in early 2026 is the unprecedented situation where both the US and China are conducting military exercises in the South China Sea "simultaneously," which has structurally increased the risk of accidental clashes. Previously, there was an unwritten rule, an implicit understanding, for both sides to stagger the timing and areas of their exercises. The breakdown of this unwritten rule has made on-site escalation management extremely difficult.