For decades, nuclear weapons have been largely peripheral to U.S.-China relations, but the nuclear relationship is now growing more competitive as both countries pursue major programs to modernize their forces. China’s efforts to strengthen its relatively small nuclear arsenal seem largely oriented toward improving survivability and do not appear to constitute a shift away from the country’s long-standing No First Use (NFU) policy. Nevertheless, the improvements are provoking anxiety in Washington, which has long resisted acknowledging a state of mutual nuclear vulnerability with China.