Ending of New Start treaty will remove mutual limits on the world’s two biggest nuclear arsenals

The New Start treaty between the US and Russia will expire on Thursday, removing the last remaining mutual limits on the world’s two biggest nuclear arsenals.

The milestone will be a death knell for more than five decades of arms control at a time of surging global instability, contributing to a general collapse of the rules-based international order established after the second world war.

Alexandra Bell, the president and chief executive of the Bulletin of the Atomic Scientists, said: “When it comes to nuclear risks, everything is trending in the wrong direction over the course of 2025. Nuclear risks have become more complex, more dangerous and we have seen leaders fail in their obligation to manage those risks.

“And we are two days away from watching the United States and Russia fritter away half a century of work to maintain nuclear stability between the two largest nuclear states.”