Russia has said it no longer considers itself bound by restrictions on its strategic nuclear arsenal as the last remaining bilateral nuclear arms control treaty between Moscow and Washington reaches its end.

In a statement issued on 4 February, the Russian foreign ministry said that, “in the current circumstances”, the parties to the New START treaty were “no longer bound by any obligations or symmetrical declarations” associated with the agreement, including its central provisions, and were “in principle free” to choose their next steps.

The ministry coupled that formulation with a warning that Russia remained ready to take what it called “decisive military-technical countermeasures” to remove potential additional threats to national security. It added, however, that Russia remained open to political and diplomatic avenues to stabilise the strategic situation, if conditions for such interaction were formed.

New START, signed in Prague in 2010 by the then US President Barack Obama and Russia’s President Dmitry Medvedev, entered into force in 2011. It capped the number of deployed strategic nuclear warheads at 1,550 per side and limited deployed and non-deployed launchers and heavy bombers, supported by verification measures including inspections and data exchanges.

The treaty was extended once, in 2021, to 4 February 2026, the latest date permitted under its terms, leaving no established legal mechanism for a further formal extension.

In practical terms, the agreement had been hollowed out well before its final day. Russia announced in February 2023 that it was “suspending” participation in New START, a move widely reported at the time as a decision to halt inspections and other verification activities while claiming it would continue to observe numerical limits.

Since then, both sides have blamed the other for the breakdown of the verification regime. With the treaty now at an end, there is no longer a legally binding framework governing the strategic nuclear forces of the world’s two largest nuclear powers.

The Russian statement on 4 February came as Moscow complained that Washington had not provided a formal response to a proposal from President Vladimir Putin to maintain the treaty’s limits for an additional year on a voluntary basis. Reuters reported that Russia said it had received no “formalised official response” from the United States and argued that its ideas were being ignored.

In parallel, President Donald Trump has signalled little appetite for taking up such a proposal. In remarks reported after an interview with The New York Times published in early January, Trump said: “If it expires, it expires … We’ll just do a better agreement.”

The end of New START also intensifies the challenge for allies and non-nuclear states seeking predictability in strategic stability. The United States and Russia still hold the bulk of the world’s nuclear warheads, and the disappearance of mutual caps and transparency measures reintroduces uncertainty about future force levels, deployments, and modernisation choices.

Arms control specialists have long warned that, without inspection rights and data exchanges, each side will have to rely more heavily on national technical means, intelligence assessments, and worst-case planning. Experts also point to the potential for follow-on effects involving other nuclear-armed states, particularly as China continues to expand and modernise its nuclear forces while remaining outside any US–Russia-style limits.

International voices have begun to weigh in. Reuters reported that Pope Leo urged both Russia and the United States not to allow the treaty to lapse and appealed for renewal to avoid a new arms race, framing the issue as a test of responsibility among major powers.

For Europe, the treaty’s expiry is likely to sharpen debate about extended deterrence, missile defence, and the credibility of security guarantees at a time when Russia’s war against Ukraine continues and nuclear rhetoric has featured repeatedly in Moscow’s messaging. The practical question is whether either side chooses to exceed previous limits, and how rapidly that could happen given production constraints, budget priorities, and competing military demands.

The Russian foreign ministry’s statement suggested Moscow would calibrate its posture in response to US military policy, while leaving open the possibility of future talks if political conditions change. For now, with New START concluded and no replacement agreement in sight, the strategic relationship is entering a period without the legal guardrails that have shaped US–Russian nuclear competition for decades.