Nulcear testing - START treaty expiring February 2026

Escalating tensions between the world’s two largest nuclear powers come only months before the last remaining US–Russia nuclear arms control treaty expires.

… The New Strategic Arms Reduction Treaty (New START) places binding limits on the number of deployed strategic nuclear warheads and delivery systems by the world’s two largest nuclear powers. It is due to expire in February 2026, risking the removal of the final guardrail restraining the size and visibility of their arsenals – and increasing the risk of a new nuclear arms race. …

If New START expires without even a symbolic extension, the consequences could be significant. The absence of mutually agreed constraints could fuel an arms race in which Russia and the US expand deployed nuclear arsenals, undermining strategic stability.

This would weaken the credibility of the Nuclear Non-Proliferation Treaty (NPT), the main international treaty governing nuclear weapons. Many states already view nuclear weapons states as backsliding on their disarmament obligations. Abandoning the last bilateral nuclear arms control framework would reinforce that perception. …

https://www.chathamhouse.org/2025/11/russia-and-us-put-nuclear-testing-back-table-time-running-out-arms-control