The United States on Friday accused China of secretly carrying out nuclear explosive tests. This comes as the New Strategic Arms Reduction Treaty (New START) between the US and Russia expired, ending limits on their nuclear arsenals. US officials are pushing for fresh arms control talks and want China included. "An arms control framework that does not include China would leave the United States and its allies 'less safe'," said US Secretary of State Marco Rubio, highlighting China’s expanding nuclear stockpile. At the UN Conference on Disarmament in Geneva, US arms control official Thomas DiNanno said, "The US government is aware that China has conducted nuclear explosive tests, including preparing for tests with designated yields in the hundreds of tons." He claimed China tried to hide these tests knowing they break their pledge to suspend nuclear testing. China strongly denied the accusations. Ambassador Shen Jian called them "false narratives and unfounded accusations," affirming China still honors its testing suspension. He accused the US of shifting responsibility for nuclear disarmament and defending "nuclear hegemony." The sharp claims came one day after New START expired. This treaty capped both countries at 1,550 nuclear warheads each. Following the expiry, Russian and US negotiators met in Abu Dhabi and agreed on the urgent need to restart arms control talks. Kremlin spokesman Dmitry Peskov said both sides want to begin negotiations "as soon as possible." Russian President Vladimir Putin offered to extend New START limits for one year if the US agreed. But US President Donald Trump wants a broader deal including China. The US and Russia have also agreed to resume high-level military talks paused since 2021. Meanwhile, China refuses to join the talks. Rubio noted China’s nuclear arsenal has grown from just over 200 warheads to more than 600 since 2020 and could exceed 1,000 by 2030. DiNanno said, "China’s entire nuclear arsenal has no limits, no transparency, no declarations and no controls." China counters that its nuclear forces are much smaller than those of the US or Russia and asks the two to bear most disarmament responsibility. Ambassador Shen urged the US to accept Russia’s proposal to temporarily maintain New START limits. US and Russia control over 80% of the world's nuclear weapons, but China’s stockpile is rapidly increasing. The lapse of New START raises fears of a new nuclear arms race with no limits now. Big differences remain: Washington demands a three-way deal with China, Moscow wants all nuclear powers included, but Beijing refuses talks so far. The world watches closely as nuclear diplomacy hangs in balance.