New START Treaty Expires, Lifting US-Russia Warhead Caps

Arms-control treaties have often withered when geopolitical mistrust outran diplomatic bandwidth: the 1979 SALT II accord was signed but never ratified after the Soviet move into Afghanistan, and the 2002 U.S. withdrawal from the ABM Treaty prompted Russia and then China to diversify delivery systems. The New START expiry fits that pattern of stepwise demolition of the Cold-War scaffolding—INF in 2019, Open Skies in 2020, now the final keystone. It also signals a structural shift from a bipolar to a triangular (U.S.–Russia–China) nuclear order in which verification is harder and brinkmanship offers domestic political payoffs. Over a 100-year horizon this moment may be remembered less for immediate warhead increases—which are costly and slow—than for normalising an unregulated strategic environment just as AI-driven targeting, hypersonic glide vehicles and space assets proliferate, shrinking decision times and raising the odds that a future crisis will mimic 1962’s knife-edge without the back-channel guardrails that once emerged from treaty negotiations.