A new report from the International Institute for Strategic Studies highlights shifting dynamics in the undersea balance between the United States and China. Between 2021 and 2025, China launched more nuclear-powered submarines than the U.S., marking a notable change from previous years. While the U.S. Navy retains a significant numerical and technological advantage — particularly in stealth and operational experience — China’s expanded production capacity and steady rollout of ballistic-missile and attack submarines signal growing momentum. Satellite imagery points to major upgrades at key Chinese shipyards, underscoring sustained industrial focus. At the same time, U.S. submarine programs face production shortfalls and delays. Analysts note that although qualitative superiority remains with Washington, rising hull numbers in the Indo-Pacific could gradually reshape regional naval calculations.