Amid an intensifying rivalry with the United States, China is modernizing and significantly expanding its nuclear forces. These developments fuel concerns that China's traditional nuclear strategy premised on a limited nuclear arsenal for assured retaliation and a no-first-use policy is undergoing a major shift. Using Chinese-language materials, an examination of Chinese debates about China's security environment and the future direction of its nuclear strategy finds that a nuclear-conventional entangled security dilemma is emerging between the United States and China. The shift in the conventional balance of force in the region and the U.S. development of lower-yield nuclear weapons has led to greater fears in China of U.S. limited nuclear use in a conflict. Chinese strategists increasingly believe that U.S. nonnuclear strategic capabilities threaten China's nuclear forces. Although there is limited evidence of a shift in its nuclear strategy, China is changing its strategic posture to ensure its second-strike capability, including by relying on advanced conventional weapons (e.g., counterspace capabilities, cyber weapons, and electronic warfare) that can target U.S. missile defense. The dynamics of an entangled security dilemma may weaken arms race stability, and they underscore why it will be challenging for the United States to engage China in nuclear arms control.