Rubio Warns China’s ‘Rapid’ Nuclear Buildup Is Making U.S. ‘Less Safe’

Secretary of State Marco Rubio warned Friday that any new U.S. nuclear treaty must reflect the rapid expansion of China’s nuclear arsenal. 

Rubio’s comments come a day after the New START Treaty, which limited deployed strategic nuclear weapons in the United States and Russia, officially expired. He argued that any replacement framework should address a new era beyond the Cold War model, one that recognized both Russia and China as nuclear peers. 

“A treaty requires at least two parties, and the choice before the United States was to bind itself unilaterally or to recognize that a new era requires a new approach. Not the same old START, but something new. A treaty that reflects that the United States could soon face not one, but two, nuclear peers in Russia and China,” he wrote on the State Department’s Substack page. 

Rubio said China’s nuclear stockpile has nearly tripled since 2020, growing from the low 200s to almost 600, with projections topping 1,000 warheads by 2030. 

“China’s rapid and opaque expansion of its nuclear arsenal since New START entered into force has rendered past models of arms control, based upon bilateral agreements between the United States and Russia, obsolete,” Rubio wrote. “An arms control arrangement that does not account for China’s build-up, which Russia is supporting, will undoubtedly leave the United States and our allies less safe.”

President Donald Trump has accused China of conducting secret nuclear tests. Under Secretary of State Thomas DiNanno said Friday on X that China had used a technique called “decoupling” to mask nuclear explosive tests by reducing the effectiveness of seismic monitoring, including one conducted on June 22, 2020.

Rubio also criticized Russia, noting that Moscow announced in 2023, amid its war with Ukraine, that it would stop recognizing the New START Treaty. Although Russia later said it would continue observing the treaty’s limits, the agreement capped deployed nuclear warheads at 1,550. 

“Russia and China should not expect the United States to stand still while they shirk their obligations and expand their nuclear forces. We will maintain a robust, credible, and modernized nuclear deterrent,” Rubio wrote. “But we will do so while pursuing all avenues to fulfill the President’s genuine desire for a world with fewer of these awful weapons.”

Ahead of New START’s expiration, President Donald Trump said he wanted a broader nuclear agreement that could include other countries like China. In a Truth Social post on Thursday, Trump criticized the Obama-era deal as poorly negotiated.

“Rather than extend ‘NEW START’ (A badly negotiated deal by the United States that, aside from everything else, is being grossly violated), we should have our Nuclear Experts work on a new, improved, and modernized Treaty that can last long into the future,” Trump wrote.