For decades, China’s nuclear deterrent relied almost exclusively on land-based missiles—static assets vulnerable to a preemptive first strike. China’s strategic submarine force remains relatively young, with doubts about its reliability. Deterring by SeaThe test was but the latest evidence of China’s progress toward developing a nuclear triad. The July test confirmed the operational readiness and performance of China’s sea-based strategic nuclear deterrent. China’s nuclear buildup is transforming global politics: making the world less predictable, complicating military planning, and eroding the arms control and nonproliferation regimes built over decades.