World Faces Higher Nuclear Risk as Last Major Arms Control Pact Ends

The expiration of the New Strategic Arms Reduction Treaty (New START) has brought the world closer to the risk of a renewed nuclear arms race, as the last major nuclear arms control pact between the United States and Russia officially ended at midnight GMT on Thursday. The treaty, along with its predecessors, had for decades placed limits on the nuclear arsenals of the world’s two largest powers.

With the lapse of New START, neither the United States nor Russia is bound by numerical caps on their deployed strategic nuclear warheads. Moscow has pledged to act responsibly but warned that it would take “decisive” measures if it perceives threats to its national security, according to the Russian Foreign Ministry. Washington, meanwhile, has not indicated that it will voluntarily maintain the treaty’s limits beyond the expiration.

The treaty, signed in 2010, restricted each side to a maximum of 1,550 deployed strategic nuclear warheads. Russian President Vladimir Putin had floated a one-year extension last year, which US President Donald Trump initially described as “a good idea,” yet no follow-up negotiations occurred. Trump has emphasized that any future arms control agreement must include China, citing Beijing’s rapidly expanding arsenal, a position Moscow considers unnecessary and China outright rejects.

In a recent video call with Chinese President Xi Jinping, Putin underscored Moscow’s intention to act in a “balanced and responsible manner” while remaining open to negotiations aimed at maintaining strategic stability. US Secretary of State Marco Rubio stated that Trump would make a final decision on the treaty later, reiterating that any deal excluding China would be unworkable. Germany’s Foreign Minister Johann Wadephul also called on Beijing to exercise restraint in weapons development, while emphasizing that future arms control frameworks must involve China.

The treaty’s expiration has drawn concern from international leaders. UN Secretary-General Antonio Guterres described the moment as a “grave threat to international peace and security,” warning that the risk of nuclear weapon use is now “the highest in decades” and urging both powers to resume negotiations immediately. Earlier, Pope Leo XIV echoed these warnings, calling on the United States and Russia not to abandon the arms control framework without ensuring that it is followed up with effective and concrete measures to prevent escalation.