China’s drive to build an all-nuclear submarine fleet is emerging as one of the most consequential shifts in the strategic balance beneath the world’s oceans, potentially extending Beijing’s naval reach from the Western Pacific into the Indian Ocean while prompting rival powers to accelerate their own undersea modernization programs.
The transformation was highlighted this month when Mike Brookes, the intelligence chief of the United States Navy, testified before the U.S.-China Economic and Security Review Commission (USCC). Brookes told lawmakers that People’s Liberation Army Navy (PLAN) is undertaking a major transition away from conventional diesel-electric submarines toward a fleet dominated by nuclear-powered boats.
The shift, he said, is part of a broader Chinese effort to strengthen undersea warfare capabilities, expand blue-water naval operations and sustain long-range patrols far beyond the country’s coastal waters.
China currently operates one of the world’s largest submarine forces, with more than 60 boats in service. The majority are conventional diesel-electric submarines, commonly known as SSKs, which are generally quieter in coastal waters but limited by shorter endurance and the need to surface or snorkel periodically.
According to Brookes, roughly 50 of China’s submarines fall into this conventional category, while the remainder include nuclear-powered attack submarines (SSNs) and ballistic-missile submarines (SSBNs).
The new strategy signals a significant departure from Beijing’s earlier reliance on large numbers of conventional submarines optimized for regional defense.
“Nuclear propulsion offers far greater endurance, speed and operational flexibility,” Brookes told the commission. Such advantages are crucial for sustained competition with advanced navies such as the United States and its allies.
Unlike diesel-electric submarines, nuclear-powered vessels can remain submerged for months, enabling them to conduct extended patrols across vast ocean distances. This capability is essential for escorting carrier strike groups, protecting sea lanes and maintaining nuclear deterrent patrols.
China’s ambitions are supported by a rapidly expanding submarine construction infrastructure.
Brookes said the country has significantly increased the size and capacity of submarine shipyards, with three major facilities expanding construction halls and production lines. The result is a shipbuilding base capable of sustaining a higher output of nuclear-powered submarines well into the 2030s.
The expansion has effectively tripled construction hall capacity and more than doubled production capability, according to US Navy intelligence assessments.
China’s massive shipbuilding industry already dominates global commercial ship construction, and the same industrial advantages are increasingly being applied to military programs.
Central to China’s transition is the development of several new classes of submarines.
One emerging design is a smaller nuclear attack submarine sometimes referred to as the Type 041 Zhou-class, intended to perform regional patrols and presence missions.
Compared with larger attack submarines, the Zhou-class is believed to be designed as a lower-cost platform capable of maintaining continuous patrols while freeing more advanced vessels for long-range operations.
At the higher end of the capability spectrum, China is developing the next generation of nuclear attack and ballistic missile submarines.
These include the Type 095 submarine, an advanced nuclear-powered attack submarine, and the Type 096 submarine, a next-generation ballistic missile submarine expected to enter service in the late 2020s or early 2030s.
According to Brookes, these submarines will incorporate quieter nuclear reactors, more advanced sonar systems and longer-range submarine-launched ballistic missiles (SLBMs).
Such improvements could enable China to conduct survivable nuclear deterrent patrols from protected waters closer to home, particularly in the South China Sea, which Beijing increasingly treats as a strategic bastion.
Despite rapid progress, analysts caution that China’s submarine industry still faces significant technological hurdles.
Sarah Kirchberger of the China Maritime Studies Institute noted in a 2023 report that Chinese submarines continue to struggle with several key engineering challenges.
These include propulsion system reliability, vibration suppression and acoustic quieting—areas in which Western and Russian submarines remain more advanced.
Acoustic quieting is particularly critical for submarines, as stealth is their primary defense. A quieter submarine is harder to detect using sonar, allowing it to track adversaries or launch missiles without revealing its position.
Kirchberger said Chinese engineers have made progress but still face difficulties in reducing vibration noise and developing advanced sound-absorbing coatings for submarine hulls.
As a result, many Chinese submarines are believed to have higher acoustic signatures than their American or Russian counterparts, potentially making them easier to detect.
If China succeeds in fielding a large nuclear submarine fleet, the strategic implications could be profound.
Nuclear-powered attack submarines could escort Chinese carrier strike groups into the wider Pacific Ocean, extending Beijing’s naval influence far beyond the so-called First Island Chain that stretches from Japan through Taiwan to the Philippines.
These submarines could also threaten US carrier groups operating in the Western Pacific, complicating any potential American intervention in a conflict over Taiwan.
In addition, nuclear ballistic missile submarines could conduct deterrent patrols from heavily defended bastions within the South China Sea, giving China a more secure second-strike nuclear capability.
Such a capability would ensure that China could retaliate even after suffering a nuclear attack, strengthening the credibility of its nuclear deterrent.
Beyond the Pacific, China’s nuclear submarines could significantly expand Beijing’s influence into the Indian Ocean, a region vital to global trade and energy supplies.
One possible mission would involve monitoring or shadowing India’s sea-based nuclear deterrent.
Relations between China and India have long been strained by unresolved border disputes in the Himalayas and periodic military confrontations along the frontier.
Both nations possess nuclear weapons, and both increasingly rely on submarine-based deterrence to ensure survivable retaliatory capability.
According to a March 2025 report by the Nuclear Threat Initiative, India plans to operate four nuclear ballistic missile submarines of the Arihant-class submarine.
The lead vessel, INS Arihant, is equipped with 12 Sagarika SLBM missiles with a range of about 700 kilometers.
However, the report says future submarines, including INS Arighat, could carry the longer-range K-4 SLBM, capable of striking targets roughly 3,500 kilometers away.
That range would allow Indian submarines to target much deeper locations within mainland China while remaining in protected patrol areas such as the Bay of Bengal.
In response, China’s nuclear attack submarines could attempt to track Indian SSBNs in much the same way that American submarines monitor Chinese ones.
China has already demonstrated that its nuclear submarines can operate far from home waters.
In 2013, a Chinese nuclear attack submarine conducted a long-range patrol through the Indian Ocean and sailed as far as the Gulf of Aden, highlighting the endurance required for distant operations in regions with limited logistical support.
Such deployments indicate that the PLAN is gradually developing the operational experience needed for sustained global submarine patrols.
Despite these ambitions, China faces major geographic barriers in reaching the Indian Ocean.
To move submarines from the South China Sea into the Indian Ocean, Chinese vessels must pass through narrow maritime chokepoints in Southeast Asia.
One of the most important is the Malacca Strait, one of the busiest shipping lanes in the world. Its shallow waters and heavy commercial traffic make covert submarine transit extremely challenging.
Other routes include the Sunda Strait, Lombok Strait, and Ombai Strait.
The Sunda Strait is shallow and cluttered with obstacles such as sandbars and oil platforms, while strong currents complicate navigation.
The Lombok Strait, at roughly 250 meters deep, allows submerged transit, while the Ombai Strait is significantly deeper—around 3,000 meters—but limited hydrological data can complicate safe navigation.
These chokepoints could become critical monitoring zones for rival navies seeking to track Chinese submarine movements.
China’s pursuit of an all-nuclear submarine fleet could also spur similar efforts among other regional powers.
India is already developing nuclear attack submarines under Project 77, which are intended to escort its ballistic missile submarines, protect carrier groups and conduct long-range strike missions.
Such submarines could also deter adversaries from deploying naval forces in the Indian Ocean.
Meanwhile, US allies in Northeast Asia are beginning to reconsider their reliance on advanced conventional submarines.
A November 2025 report by the S. Rajaratnam School of International Studies, co-authored by maritime analyst John Bradford, found that Japan and South Korea are exploring the possibility of nuclear-powered submarines.
Both countries currently operate sophisticated diesel-electric fleets that are among the most advanced in the world. However, deteriorating regional security conditions and the rapid expansion of Chinese naval capabilities are prompting new debates about nuclear propulsion.
Nuclear submarines offer higher speeds, longer endurance and greater operational flexibility for distant patrols and sea-lane defense.
Nevertheless, political, financial and technological barriers remain substantial.
South Korea must address nuclear fuel restrictions under its 2015 agreement with the United States before pursuing such submarines, while Japan faces domestic opposition to military applications of nuclear technology.
Another factor shaping the regional submarine balance is the future of Australia’s nuclear submarine program under the AUKUS partnership with the United States and the United Kingdom.
Under current plans, Australia is expected to acquire several nuclear-powered submarines based on the American Virginia-class submarine design.
However, a January 2026 report by the Congressional Research Service suggested an alternative arrangement.
Instead of selling submarines to Australia, the United States could retain additional Virginia-class boats for its own fleet while deploying them from Australian bases.
In that scenario, American submarines would carry out many of the missions originally intended for Australian vessels, while Australia focuses on other capabilities supporting the alliance.
US and British submarines would still rotate through Western Australia under this approach, maintaining a persistent allied submarine presence in the region.
Whether China ultimately succeeds in building a fully nuclear-powered submarine fleet remains uncertain.
The transition requires enormous financial investment, advanced engineering expertise and decades of operational experience.
Yet if Beijing overcomes these challenges, the strategic consequences could reshape the Indo-Pacific security environment.
A large Chinese nuclear submarine fleet could operate across vast ocean distances, escort aircraft carriers, threaten rival naval forces and maintain continuous nuclear deterrent patrols.
At the same time, it could trigger a broader regional contest beneath the waves, as countries across the Indo-Pacific race to enhance their own submarine capabilities.
