New START Expiration Ends U.S.-Russia Nuclear Limits

New START, the 2010 U.S.-Russia arms control treaty, expired on Feb. 5, 2026, ending binding limits of 1,550 strategic warheads per side. The lapse removes on-site inspections and data exchanges, raising risks of an unpredictable three-way nuclear buildup involving the United States, Russia and China. Experts warn it increases nuclear dangers and pressures policymakers to pursue new multilateral restraints and verification mechanisms.