New START Expired With No Successor, Ending All Nuclear Arms Limits

The New START treaty expired on February 5, 2026, without a replacement or extension, marking the first time since 1972 that no legally binding agreement limits the nuclear arsenals of the United States and Russia. Russia had offered an informal one-year extension of force limits in late 2025, but the Trump administration -- seeking a broader deal that would include China -- never formally responded. On February 4, 2026, Russia's Ministry of Foreign Affairs declared the treaty's obligations no longer binding. The collapse of New START is the final stage in the systematic dismantling of the arms control architecture: the ABM Treaty ended in 2002, the INF Treaty collapsed in 2019, and now the last remaining bilateral nuclear constraint is gone. This matters because arms control treaties are not just about limiting warhead counts -- they provide transparency, predictability, and verification mechanisms that reduce the risk of miscalculation. Under New START, both sides conducted up to 18 on-site inspections per year of each other's nuclear facilities. Those inspections provided direct intelligence about the other side's nuclear posture that no satellite or signals intelligence can replicate. Without them, both nations must rely on national technical means that are inherently less precise, increasing the risk that ambiguous intelligence is misinterpreted as a threat. The immediate practical consequence is that both the U.S. and Russia are now free to deploy more strategic nuclear weapons without any legal constraint. Russia has already indicated it will determine its force structure based on 'the evolving strategic environment,' a diplomatic signal that uploading additional warheads onto existing delivery systems is under consideration. The U.S. is simultaneously modernizing all three legs of its nuclear triad -- new ICBMs, new submarines, new bombers, new warheads -- at a projected cost of $1.5-2 trillion over 30 years. The structural reason arms control collapsed is the emergence of a tripolar nuclear dynamic that bilateral treaties cannot address. China is rapidly expanding its nuclear arsenal from approximately 500 warheads toward an estimated 1,000-1,500 by 2035, and has refused to participate in arms control negotiations, arguing its arsenal is too small to warrant limits. Russia will not accept constraints that do not account for Chinese capabilities on its border. The U.S. wants a trilateral framework but has no mechanism to compel Chinese participation. This three-body problem in nuclear diplomacy has no precedent and no obvious solution. The risk is a return to an open-ended nuclear arms competition among three major powers, with no verification, no transparency, and no agreed rules -- the most dangerous nuclear environment since the early 1960s before the first arms control agreements were reached.