China's All-Nuke Sub Push May Trigger An Undersea Arms Race

As Sarah Kirchberger notes in a September 2023 report for the China Maritime Studies Institute (CMSI), China's submarine industrial base still faces significant technological challenges in propulsion systems and acoustic quieting, areas in which Western and Russian submarines remain more advanced.

She notes that Chinese engineers have struggled with vibration suppression, noise reduction, and sound-absorbing coatings, factors that contribute to comparatively higher acoustic signatures.

Nevertheless, an all-nuclear submarine fleet could give China the capability to escort its carrier strike groups (CSGs) out into the Pacific, threaten US carriers operating beyond the First Island Chain to dissuade US and allied intervention in the event of a conflict over Taiwan, and enable continuous SSBN patrols within heavily defended bastions in the South China Sea for second-strike nuclear capability.

Beyond those applications, an all-nuclear submarine force could project China's power into the Indian Ocean. China might use nuclear submarines to threaten India's sea-based deterrent. China and India have longstanding border disputes in the Himalayas, marked by skirmishes and the potential for full-scale conflict between nuclear-armed states.

According to a March 2025 Nuclear Threat Initiative (NTI) report, India plans to field four Arihant-class SSBNs, with the lead boat, INS Arihant, armed with 12 Sagarika submarine-launched ballistic missiles (SLBMs) with a range of about 700 kilometers-limited to targets in western or southwestern China when launched from protected bastions in the Bay of Bengal.

However, the NTI report notes that Arihant's successors, including INS Arighat, could be armed with the longer-range K-4 SLBM, with a range of roughly 3,500 kilometers, enabling strikes against targets deep inside mainland China.

Hence, China could use its SSNs to shadow India's SSBNs in the Bay of Bengal, much as the US Navy's SSNs possibly shadow China's SSBNs in the South China Sea.

Underscoring that possibility, in 2013, a Chinese SSN completed a patrol in the Indian Ocean and sailed all the way to the Gulf of Aden, showing the endurance needed for long-range patrols in regions with limited resupply options.

Still, China faces geographic barriers to accessing the Indian Ocean, requiring passage through strategic chokepoints such as the Malacca, Lombok, Sunda, and Ombai Straits.

The Malacca Strait's shallow depth and heavy traffic complicate covert submarine transit. The Sunda Strait's even shallower depth, strong currents, and obstacles such as sandbars and oil platforms make passage difficult. While the Lombok (~250 meters deep) and Ombai (~3,000 meters deep) Straits allow submerged transit, limited hydrological data complicates navigation.

China's push for an all-nuclear submarine fleet could spur similar efforts in India and other Pacific countries such as Japan, South Korea, and Australia.

Similar to China, India's upcoming Project 77 SSNs could escort its SSBNs in its Bay of Bengal bastions, escort its CSGs in the Indian Ocean, support long-range strike operations with submarine-launched cruise missiles, and deter adversaries from deploying naval forces in the Indian Ocean.

Aside from India, Japan and South Korea could take notice of China's efforts to build an all-nuclear submarine fleet. As noted by John Bradford and other writers in a November 2025 report for the S. Rajaratnam School of International Studies (RSIS), Japan and South Korea are reconsidering their longstanding reliance on advanced conventional submarines amid a deteriorating regional security environment and the expansion of military capabilities among potential adversaries.