U.S.-China Nuclear Competition Beneath the South China Sea

Key Points :

• Roughly $3.4 trillion in trade passes through the South China Sea annually, yet both the U.S. and China keep investing in nuclear submarines because deterrence, not war, is the stated goal.
• China’s Bastion doctrine is not coastal defense. The JL-3 missile gives Type 094 submarines the range to threaten the U.S. mainland from near-littoral waters.
• AUKUS forward basing at HMAS Stirling is designed to cut U.S. operational costs by 30 to 40 percent and shift from rotational to persistent allied presence near contested waters.
• Washington has extended nuclear propulsion technology to South Korea and deepened Japan’s undersea role, forming a de facto AUKUS-Plus coalition that Beijing views as deliberate encirclement.
• China is unlikely to initiate a military crisis within 15 to 20 years given current military disadvantages; its preferred competition arena remains economic and technological.
• The most plausible escalation path is an accident or misread, not a deliberate first strike: a collision, an uncharted seamount, a faulty sensor in waters where communication is limited and attribution is contested.
• A South China Sea trade disruption would cascade directly into European supply chains, freight costs and energy prices.

Strategic Context: $3.4 Trillion and the Paradox of Deterrence

Would the United States deliberately start a conflict in the South China Sea? The economic logic says no. China ships its exports through these waters. The United States and China traded roughly $659 billion in goods and services in 2024 alone^[1]. A shooting war would inflict generational damage on both economies. And yet both governments are quietly pouring money into the most dangerous and least visible instrument of maritime power: nuclear submarines.

Security strategies are not shaped only by today’s trade figures but by the “what if things go wrong” scenario. If one side can credibly threaten the other’s sea lanes, carriers or second-strike capability, it gains leverage in every negotiation short of war. Submarines, invisible, untraceable and lethal, are the ultimate tool for generating that leverage without announcing it. In deterrence theory, they generate leverage not by signaling loudly but by being plausibly present, which is precisely why they can stabilize bargaining while also increasing the penalties for misperceptiony.^[2]

The South China Sea sits at the center of this logic. More than 30 percent of global maritime crude oil trade passed through these waters in 2016, with over 90 percent of that volume transiting the Strait of Malacca.^[3] China’s dependence on this corridor, the so-called “Malacca Dilemma,” is a structural vulnerability that shapes every layer of Beijing’s maritime strategy. Energy flows and container traffic concentrate at chokepoints that any capable submarine force can threaten, making deterrence not just desirable but structurally necessary for both sides.^[4]

China’s Bastion Doctrine: From Coastal Defense to Continental Strike

China’s undersea buildup is not a conventional naval modernization story. It is a nuclear deterrence project. The People’s Liberation Army Navy currently operates six nuclear ballistic missile submarines alongside six nuclear attack submarines and roughly 48 diesel and AIP-powered boats, with the broader fleet projected to reach 80 submarines by 2035.^[5] In the early 2000s, China’s submarine force numbered around 40 to 45 boats, most based on aging Soviet designs. That force has been systematically transformed through the Type 039A/B Yuan-class AIP submarines, the Type 093 nuclear attack boats and the Type 094 ballistic missile submarines. The ongoing Type 096 program shows that Beijing is now focused on qualitative advancement, prioritizing quieting, range and survivability over sheer platform numbers.

The strategic shift comes from missile range paired with geography. The older JL-2 missile required Chinese SSBNs to patrol mid-Pacific waters to threaten the continental United States, while PRC sources claim the JL-3 exceeds 5,400 nautical miles, enabling targeting of portions of the continental United States from PRC littoral waters.^[5] The U.S. Department of Defense further assesses that China has probably fielded the JL-3 on the Jin class, enabling the navy to consider bastion operations in the South China Sea and Bohai Gulf to enhance survivability of the sea-based deterrent. This transforms the Bastion doctrine from a near-shore defensive concept into a genuine second-strike instrument capable of holding American cities at risk with minimal warning time.

The next-generation Type 096 SSBN, expected to enter service in the late 2020s or early 2030s, is designed to carry multiple independently targetable reentry vehicles.^[5] Adversary anti-submarine warfare efforts must either accept a higher probability of failure or attempt to penetrate defended Chinese bastions, an act Beijing could plausibly interpret as undermining second-strike assurance, compressing crisis decision space dangerously.^[6]

China has historically fought as a land-defense power and has accumulated little real-world submarine combat experience. Platform numbers and technical specifications tell only part of the story; crew proficiency, realistic training and institutional knowledge built over decades at sea are equally decisive factors.^[7] Chinese nuclear submarines lagged American boats in acoustic discretion, and while incremental improvements are documented in the Type 093 variants,^[8] a meaningful capability gap with leading U.S. platforms remains.^[9]

AUKUS and the Alliance Response: Persistence Over Presence

AUKUS is routinely framed as a technology transfer agreement, but its most immediate operational logic is about geography and cost. Nuclear submarines operating from home ports in the eastern Pacific spend a substantial fraction of each deployment in transit rather than on station. Moving sustainment infrastructure to HMAS Stirling in Western Australia, where up to four U.S. and one UK nuclear-powered submarine will rotate from as early as 2027 as “Submarine Rotational Force West,”^[10] shifts this arithmetic considerably. The arrangement is designed not merely to add another ally to the operational theater but to cut U.S. logistics costs by an estimated 30 to 40 percent and replace rotational force deployments with something closer to a permanent allied presence.

The structural constraint is industrial. Virginia-class production has averaged roughly 1.1 to 1.2 boats per year against a stated goal of two, well below the approximately 2.33 per year necessary to meet both U.S. requirements and AUKUS commitments.^[11] Each Virginia-class hull with the Virginia Payload Module runs to about $5 billion, with reactor maintenance costs of roughly $1 billion every five years. Defense exports and allied dependency on U.S. platforms represent a long-term strategic asset for Washington: allied navies that invest in American nuclear submarine ecosystems become integrated into U.S. maintenance, training and logistics networks for decades.

On the industry side, the UK stands to gain substantially from submarine construction and technology agreements under AUKUS. European defense firms have faced headwinds in this environment. With AUKUS shouldering the nuclear deterrence role in the region, countries such as the Philippines and Malaysia are shifting procurement toward AIP-equipped submarines rather than conventional diesel platforms. This reorientation, driven by the region’s rising demand for extended submerged endurance and strategic depth, represents a market opening that manufacturers such as TKMS of Germany, Thales of France and Rheinmetall are now seeking to exploit with advanced conventional offerings tailored to those requirements.

The framework has since expanded into AUKUS-Plus. In 2025, Washington extended nuclear propulsion technology to South Korea and deepened Japan’s Pillar II involvement in advanced undersea projects. South Korea plans to build nuclear-powered attack submarines with U.S. support, partly through the Hanwha-operated Philadelphia shipyard, channeling approximately $150 billion into American naval construction. In July 2023, the United States sent an Ohio-class SSBN to Busan, the first such visit in four decades, signaling the direction of travel. Japan has not committed to SSNs but is expanding its AIP-equipped conventional fleet and integrating industrially with allied programs. From Beijing’s perspective, each of these moves erodes China’s ability to protect its bastion areas and sea lines of communication, prompting calls within Chinese strategic circles to accelerate the Type 096 program and deepen naval cooperation with Russia.

Nuclear Submarines in a Possible Taiwan Crisis

The Taiwan crisis is increasingly a submarine supremacy contest, though not in the way popular coverage suggests. The Taiwan Strait itself, roughly 300 kilometers long, 200 kilometers wide and averaging only about 60 meters in depth,^[12] is operationally hostile territory for nuclear submarines. Shallow water creates intense acoustic effects and severely constrains passive sonar performance. The strait also carried 44 percent of the world’s container fleet in 2022,^[13] generating merchant noise that degrades underwater sensing for both sides. Nuclear submarine operations in the strait’s center are effectively impractical. The real undersea competition plays out in the deeper approaches to the north and south, where submarines can maneuver, trail surface forces and threaten reinforcements.^[14]

Seafloor mapping compounds the risk. As of mid-2025, only about 27 percent of the global ocean floor had been surveyed to modern high-resolution standards.^[15] The USS Connecticut’s 2021 grounding on an uncharted seamount in the Indo-Pacific, a preventable incident attributed to navigation planning and watch-standing failures,^[16] illustrates that even the world’s most capable submarine force is not immune to incomplete bathymetric data. In a crisis, a comparable incident involving trailing submarines would be far more politically combustible than a surface vessel scrape, because attribution and intent would be immediately contested.

Global Stakes: European Supply Chains and Economic Risk

Military competition in the South China Sea does not stay in the South China Sea. Chinese exports to Europe travel largely by sea, passing through the Malacca Strait and the Suez Canal before reaching European ports. A disruption to these routes would affect not only the volume of goods flowing westward but the production planning, inventory costs, delivery timelines and price stability of European manufacturers dependent on Asian components. Energy prices would face additional pressure as Asian crude oil flows were rerouted or delayed.

From a European strategic perspective, the South China Sea is a remote theater with direct economic exposure. Any scenario that closes or seriously threatens the Malacca chokepoint creates immediate freight rate increases, supply chain delays and risk premiums that cascade through European industry. Maritime strategy can no longer be treated as a regional concern; it is an integral part of global trade security and must be understood as such by European policymakers.

Possible Scenarios In The Region

The most probable near-term trajectory is controlled rivalry. Both sides will continue building capability and signaling resolve without deliberately crossing into open conflict. China will likely conduct longer submarine patrols and may showcase the Type 096 program as a deterrent signal. The United States and allies will accelerate Virginia-class and Columbia-class construction and deepen forward posture through AUKUS.

China is unlikely to initiate a military crisis of its own volition within the next 15 to 20 years. Beijing’s current strategic preference is to compete through economic strength and technological advancement rather than to accept military risk while still at a disadvantage in undersea warfare experience and platform quieting. The United States, by contrast, views China as a potential peer competitor within that timeframe and frames its submarine investments accordingly. Each side is thus shaping a competition whose most dangerous outcomes are likely to be unintended rather than deliberate.

The risk is not deliberate escalation but miscalculation. A submarine collision, a misread sonar contact, an incident involving allied vessels near a Chinese bastion area; any of these could generate political pressure that outpaces the communication channels available to manage it. The Taiwan Strait approaches, the Spratly Islands and the waters around the Korean Peninsula are all environments where that kind of incident is statistically plausible. Clear rules of engagement, dedicated sub-safety communication channels and confidence-building measures could help prevent mishaps from spiraling, but these mechanisms remain underdeveloped relative to the pace of undersea competition.

This strategic restraint has also been reflected in recent Chinese diplomatic messaging. Following the U.S. strike on Iran in early 2026, Chinese Foreign Minister Wang Yi reiterated that external powers should avoid actions that could destabilize critical regions and warned that great-power rivalry must not escalate into open confrontation. In the same statement, Beijing again emphasized that Taiwan remains an internal matter and that no external actor should attempt to alter the strategic balance in the Indo-Pacific. The message is a clear reminder that while China seeks to avoid immediate military escalation, it will continue to signal firm resolve regarding sovereignty and regional security architecture. In the context of undersea competition, such diplomatic signals serve a dual function: they reinforce deterrence credibility without triggering the very escalation Beijing claims to oppose, and they build political cover for further acceleration of the Type 096 program by framing it as a defensive response to external pressure.

Conclusion

Nuclear submarines in the South China Sea function as the most consequential instruments of deterrence in the Indo-Pacific: present enough to constrain adversary decision-making, invisible enough to avoid triggering the escalation they are designed to prevent. Both the United States and China are investing in this capability not because war is the plan but because neither side can afford to cede undersea leverage if deterrence erodes. The danger lies in the same properties that make submarines strategically indispensable, namely their invisibility, persistence and proximity to contested waters, which also make accidents and misidentification more consequential. Managing this competition requires not just capable undersea forces but the crisis communication infrastructure and strategic patience to prevent a navigational incident or a misread sonar contact from outpacing the political channels available to contain it.

References

1. Office of the U.S. Trade Representative, China — ustr.gov
2. Jervis, R., Cooperation under the Security Dilemma — sfu.ca
3. U.S. EIA, South China Sea Energy Flows — eia.gov
4. CSIS China Power, How Much Trade Transits the South China Sea? — chinapower.csis.org
5. U.S. DoD, Military and Security Developments Involving the PRC 2024 — media.defense.gov
6. Carnegie Endowment, China SSBN Evolution and Strategic Stability (Zhao) — carnegieendowment.org
7. Congressional Research Service, China Naval Modernization, R46808 — congress.gov
8. CMSI, A Brief Technical History of PLAN Nuclear Submarines (Carlson and Wang, 2023) — andrewerickson.com
9. Federation of American Scientists, Submarine Noise Comparison — fas.org
10. Australian Submarine Agency, Submarine Rotational Force West — asa.gov.au
11. Congressional Research Service, Virginia-class Submarines, RL32418 — congress.gov
12. Tidal Propagation and Dissipation in the Taiwan Strait, ScienceDirect — sciencedirect.com
13. USNI Proceedings, Taiwan Strait: The Ocean’s Most Contested Place (Nov 2023) — usni.org
14. USNI Proceedings, You Can’t Win Without More Submarines (Dec 2023) — usni.org
15. NOAA, ETOPO Global Relief Model — ncei.noaa.gov
16. U.S. Navy, USS Connecticut Command Investigation — navy.mil
17. U.S. Navy, Fleet Ballistic Missile Submarines Fact File — navy.mil
18. U.S. Navy, Fleet Ballistic Missile Submarines Fact File — navy.mil