GENEVA—China is resisting bilateral talks with the United States on nuclear weapons, the U.S. disarmament ambassador told a U.N. conference on Tuesday, as Washington seeks to advance efforts to reduce nuclear arms stockpiles. “Despite the PRC’s dramatic build-up of its nuclear arsenal, unfortunately it continues to resist discussing nuclear risk reduction bilaterally with the United States,” said Robert Wood, referring to the People’s Republic of China. “To date Beijing has not been willing to engage meaningfully or establish expert discussions similar to those we have with Russia. We sincerely hope that will change,” he added. In an apparent rebuttal, China’s envoy later told the same virtual U.N. meeting that Beijing was prepared for dialogue. “We stand ready to carry out positive dialogue and exchange with all parties to jointly explore effective measures to reduce nuclear risk and to contribute to global strategic security,” Ji Zhaoyu said. The exchange came at …