Why US-China Tensions Are Rising in the South China Sea and the Wider Pacific
Warships, coast guard cutters, and aircraft now shadow each other almost daily in the South China Sea. Chinese patrols circle disputed reefs and shoals. US carrier strike groups launch jets from nearby waters to assert that these seas remain open to all. Each operation is framed as routine. Each also carries the risk of miscalculation.
The tension between the United States and China over these waters has spilled into the wider Pacific, from the Philippines to the Solomon Islands. What began as a regional dispute over reefs and rocks has become a test of whose rules will shape the Indo-Pacific order: a China-centered sphere of influence or a system built around international law and US-led alliances.
This article explains how the South China Sea dispute developed, why it now overlaps with competition across the broader Pacific, and what is at stake for global trade, security, and everyday lives. It looks at the historical roots, the political and economic drivers, and the possible paths ahead.
Key Points
The US-China dispute in the South China Sea centers on overlapping maritime claims, control of key sea lanes, and the future balance of power in Asia.
China’s “nine-dash line” and extensive maritime claims clash with the rights of Southeast Asian states under international law, as well as with US naval operations.
A 2016 international tribunal ruling rejected much of China’s maritime claim, but Beijing has ignored the decision while building artificial islands and expanding patrols.
The United States does not claim territory in the South China Sea but conducts regular “freedom of navigation” operations and deepens security ties with allies such as the Philippines and Japan.
Competition has spread into the wider Pacific, where both Washington and Beijing are courting Pacific Island states with security, aid, and infrastructure deals.
The risk is not only a direct clash between US and Chinese forces, but also growing pressure on smaller states, disrupted trade, and long-term militarization of a region already vulnerable to climate change.
Background
The South China Sea is a semi-enclosed sea bordered by China, Vietnam, the Philippines, Malaysia, Brunei, and Taiwan. It is one of the world’s busiest maritime corridors, carrying an estimated trillions of dollars in annual trade, including vital energy and goods flows between East Asia and the rest of the world. The broader Pacific, including the island states of Oceania, provides depth and access routes for both US and Chinese forces.
After World War II, the United States emerged as the dominant naval power in the Pacific, building alliances with Japan, South Korea, the Philippines, Australia, and others. Over the same period, China began to assert what it sees as historic rights in surrounding seas. By the mid-20th century, Chinese maps were already showing a sweeping “nine-dash line” that loops deep into the South China Sea, overlapping with the internationally recognized exclusive economic zones (EEZs) of Southeast Asian states.
Tensions sharpened as China’s power grew. From the 1990s onward, there were repeated standoffs over reefs, shoals, and fishing grounds. In the 2010s, Beijing began large-scale land reclamation, turning submerged features into artificial islands with runways, radar installations, and missile sites. This shifted the facts on the water by giving China more capacity to monitor and, if it chose, to control nearby sea lanes.
In 2013, the Philippines brought a case against China under the UN Convention on the Law of the Sea (UNCLOS). In 2016, an international tribunal ruled overwhelmingly in Manila’s favor, stating that China’s “historic rights” claims within the nine-dash line had no legal basis where they exceeded maritime zones allowed under UNCLOS. The award also found that several contested features were legally rocks or low-tide elevations, limiting their ability to generate maritime zones. China rejected the ruling as “null and void” and has refused to comply.
The United States, while not a claimant state and not party to UNCLOS itself, has long run a global “freedom of navigation” program. In the South China Sea, US destroyers and other vessels deliberately sail near features claimed by China and others to challenge what Washington sees as excessive maritime claims. These operations increased after 2015 and continue today, often prompting sharp protests and close intercepts by Chinese forces.
Meanwhile, competition has spilled into the wider Pacific. A 2022 security pact between China and the Solomon Islands raised concerns in Washington, Canberra, and Wellington about the possibility of Chinese military access in a region long dominated by US and allied forces. Since then, both China and Western partners have signed or expanded security and economic agreements with Pacific Island states, turning the region into another arena of great-power rivalry.
Analysis
Political and Geopolitical Dimensions
For China’s leadership, the South China Sea touches on sovereignty, security, and national pride. Beijing frames its actions as defending “territorial integrity” and undoing what it sees as a legacy of humiliation by foreign powers. Control of nearby seas is also viewed as essential to protecting China’s long coastline, submarine bases, and sea lines of communication for energy and trade.
For the United States, the issue is less about specific reefs and more about upholding a broader order. Washington insists that maritime rights must follow international law, not unilateral claims, and that major sea lanes must remain open to all. It has treaty obligations to defend the Philippines in the event of an armed attack on its forces or public vessels, and security partnerships with Japan and other allies that depend on credible US presence in the region.
In recent years, frictions have intensified at flashpoints such as Scarborough Shoal and Second Thomas Shoal, both within the Philippines’ EEZ but also claimed by China. Chinese coast guard and maritime militia vessels have been accused of using water cannons, dangerous maneuvers, ramming, and even cutting equipment cables against Philippine ships. Manila has responded by publicizing incidents, reinforcing legal claims, and deepening military ties with the US and other partners.
The US has backed the Philippines with joint patrols, expanded access to bases, and new funding for naval facilities near the South China Sea. Japan and Australia have joined some of these activities, signaling a wider coalition concerned about Chinese behavior at sea. Beijing, for its part, has framed these moves as encirclement and interference by outside powers, while stepping up its own naval and coast guard patrols in disputed waters.
This dynamic extends into the broader Pacific. Pacific Island governments, once seen as a quiet strategic backwater, now find themselves courted by both sides. China offers infrastructure, policing assistance, and investment. The US and allies respond with renewed aid, security cooperation, and high-level visits. Each side says it is supporting development and stability, but local leaders also warn that their countries risk becoming pawns in a larger struggle
Economic and Market Impact
The South China Sea is a key artery for global trade. Disruption there would affect shipping costs, insurance premiums, and the reliability of supply chains from East Asian factories to markets worldwide. Even without open conflict, sustained tension encourages businesses and governments to think about diversifying routes and suppliers, adding friction to global commerce.
The sea is also rich in fish stocks and believed to hold significant oil and gas reserves. For coastal states, fisheries are vital for food security and livelihoods. Competition over fishing rights has fueled clashes involving coast guards, fishing fleets, and paramilitary vessels. In the broader Pacific, concerns about illegal, unreported, and unregulated fishing—often linked to distant-water fleets—are pushing island states to seek outside patrol support and better monitoring technology.
Energy exploration is more constrained by technical and financial factors, but the possibility of offshore resources adds another layer of incentive for states to secure maritime zones. Pipelines, undersea cables, and planned energy projects all depend on a predictable security environment. Investors watch this closely when deciding where to commit capital.
Technological and Security Implications
The South China Sea has become a testing ground for new military concepts. China’s artificial islands host runways, hangars, radars, and missile systems that extend its surveillance and strike range. These outposts do not guarantee control of the sea in wartime, but they complicate US and allied planning and increase the risk that any crisis would feature rapid escalation in a small space. Council on Foreign Relations
The US response blends presence, partnerships, and emerging technologies. Regular freedom of navigation operations, submarine patrols, and carrier deployments signal that Washington will not accept closed seas. At the same time, the US is experimenting with more distributed forces, including mobile anti-ship missiles deployed during exercises in the Philippines—systems designed to threaten large warships from land in a future conflict.
Cyber operations, satellite surveillance, and electronic warfare add invisible layers to the competition. Both sides invest in the ability to track, jam, or blind the other’s forces. These tools create new ways to signal resolve but also new avenues for miscalculation, especially if non-kinetic actions are misread as precursors to attack.
Social and Cultural Fallout
Although the dispute centers on maps and maritime law, it also feeds into nationalism. State media, online influencers, and political leaders in both countries use incidents at sea to rally domestic support. In China, coverage often highlights foreign “provocations” and the need to defend sovereignty. In the US, the narrative tends to focus on resisting authoritarian expansion and supporting allies.
People-to-people ties—students, tourists, business travelers—have been affected by the broader downturn in US-China relations. Visa restrictions, political rhetoric, and suspicion around technology and research cooperation all make it harder to separate maritime tensions from the wider relationship. For smaller countries in Southeast Asia and the Pacific, the cultural impact can be more subtle: foreign bases, visiting troops, and new policing programs change local perceptions of security and sovereignty.
Why This Matters
The most obvious risk is a collision or confrontation at sea spiraling out of control. Close encounters between ships and aircraft are now common. If lives are lost or major vessels damaged, political pressure on both sides could make de-escalation harder, especially in an environment of mutual distrust.
Beyond crisis scenarios, the long-term militarization of the South China Sea and the wider Pacific could lock the region into an arms race. Countries may feel compelled to buy more ships, missiles, and surveillance systems rather than spending scarce resources on climate resilience, health, or education. For Pacific Island states already facing rising seas and extreme weather, this trade-off is particularly stark.
The dispute also tests the future of international law. The 2016 arbitration ruling showed that smaller states can use legal mechanisms to challenge larger powers. But China’s refusal to accept the decision, and the limited tools available to enforce it, raise questions about how effective such rulings really are when they clash with core strategic interests. The way this plays out will influence how other countries think about treaties and tribunals in future disputes.
Finally, the South China Sea and the surrounding Pacific sit at the center of a broader shift toward a more contested, multipolar world. How Washington and Beijing manage their rivalry here will shape perceptions in Europe, Africa, and Latin America about whether major powers can compete without tipping into open conflict.
Real-World Impact
Consider a fishing community on the Philippine coast. For generations, families relied on nearby shoals for their catch. Now, frequent confrontations with larger coast guard vessels and distant-water fleets make those waters feel dangerous. Boats may be damaged or turned away. Fuel costs rise as crews travel farther, and income becomes less predictable. That instability feeds into local politics and migration decisions.
In a small Pacific Island capital, officials weigh new offers of loans and security cooperation. A proposal from one major power promises a port upgrade and police training. A rival offer includes climate finance and patrol boats. Each deal comes with expectations about UN votes, port access, or training exercises. Leaders must balance national development needs with the risk of being drawn too far into one camp.
A global shipping company looks at its insurance premiums. Reports of close calls, coercive inspections, or potential sanctions make some routes seem riskier. The firm might choose to diversify ports of call, shift to alternative routes where possible, or demand higher rates for cargo moving through contested waters. Those decisions ripple down to consumers in the form of higher prices or delayed deliveries.
Even far from the Pacific, a pension fund or investment firm tracks developments in the South China Sea as part of geopolitical risk assessments. Escalation could affect markets, energy prices, and the value of assets tied to Asian growth. What looks like a distant maritime dispute can soon show up in portfolios and job markets.
Conclusion
At its core, the tension between the United States and China over the South China Sea and the surrounding Pacific is about whose rules will shape one of the world’s most strategic regions. For China, this is a question of sovereignty, security, and historical redress. For the US and its allies, it is about defending an open maritime order and reassuring partners that treaties still mean something.
The choices ahead are stark but not predetermined. The two powers can continue the current path of incremental escalation, more patrols, and deeper mistrust. They can also seek practical arrangements: clearer protocols for encounters at sea, more transparent communication in crises, and progress on long-discussed regional codes of conduct. Smaller states will keep pushing for space to protect their own interests rather than simply choosing sides.
In the coming years, the key signals to watch will include the intensity of close encounters at sea, new security deals with Pacific Island states, the pace of military deployments in the region, and any renewed diplomatic efforts to manage disputes. The South China Sea may remain contested, but how that contest is handled will help decide whether the Indo-Pacific becomes a zone of managed rivalry—or the flashpoint for a broader conflict.
