The New START (Strategic Arms Reduction Treaty), the final major nuclear arms control agreement between the United States and Russia, has officially expired today, February 5, 2026. Despite last-minute appeals from international mediators, the treaty was not extended, removing the remaining legal limits on the world’s two largest nuclear arsenals. 

United Nations Secretary-General António Guterres warned that this marks a "very dangerous moment" for global stability, as it could trigger a new unfettered arms race. Both nations have expressed a willingness to discuss a future framework, but ongoing tensions over the conflict in Ukraine have stalled formal negotiations. This expiration leaves the global community without a verification mechanism for nuclear warhead deployments for the first time in decades.