US-Russia 'New START' Treaty Formally Expires; Global Nuclear Disarmament Architecture Faces Collapse

On February 5, 2026, the New START treaty, the last remaining nuclear arms limitation agreement between the US and Russia, expired without renewal. Since 2011, the treaty has capped deployed strategic nuclear warheads. Its expiration removes formal inspection mechanisms and constraints, triggering deep international fears of a renewed nuclear arms race. The UN Secretary-General warned that global security is at its most vulnerable point in decades.