The Last Treaty Falls: New START Expires and the World Enters Uncharted Nuclear Territory

At midnight on February 5, 2026, the last remaining nuclear arms control treaty between the United States and Russia officially expired. For the first time in more than half a century, the world's two largest nuclear arsenals are operating without any legally binding limits, verification mechanisms, or mutual transparency requirements.

The New Strategic Arms Reduction Treaty, known as New START, had capped deployed strategic nuclear warheads at 1,550 for each country since 2011. It was, by any measure, a modest agreement. It did not eliminate nuclear weapons. It did not even dramatically reduce them. What it did was provide a framework for the two countries that together possess roughly 90% of the world's nuclear weapons to keep track of what the other was doing.

That framework is now gone, and nobody seems particularly concerned about replacing it.

How We Got Here

New START was negotiated by the Obama administration and signed in Prague in 2010 by President Barack Obama and Russian President Dmitry Medvedev. It was designed to last ten years, with an option for a five-year extension. In 2021, in one of his first acts as president, Joe Biden exercised that option, pushing the treaty's expiration to February 2026.

The extension was supposed to provide time for negotiating a replacement. That negotiation never happened. Russia invaded Ukraine in February 2022, and arms control discussions became casualties of the broader collapse in U.S.-Russian relations. Moscow suspended its participation in the treaty in early 2023, citing American support for Ukraine, though it claimed it would continue observing the treaty's numerical limits.

In September 2025, Russian President Vladimir Putin offered to continue observing New START limits for one year after expiration, provided the United States made a reciprocal commitment. President Donald Trump, who had returned to office in January 2025, called the offer "a good idea" but never formally responded. Russia interpreted the silence as rejection.

On Thursday, as the treaty expired, Trump posted on Truth Social: "Rather than extend 'NEW START' (A badly negotiated deal by the United States that, aside from everything else, is being grossly violated), we should have our Nuclear Experts work on a new, improved, and modernized Treaty that can last long into the future."

What this new treaty might look like, when it might be negotiated, and who might participate are questions Trump did not address.

The China Question

Secretary of State Marco Rubio has made clear that any future arms control agreement must include China. "The president's been clear in the past that in order to have true arms control in the 21st century, it's impossible to do something without China," Rubio said at a press conference on Wednesday.

This position is not without logic. China's nuclear arsenal is growing rapidly, with estimates suggesting it could reach 1,500 warheads by 2035, roughly matching the limits that New START had imposed on Russia and the United States. Including Beijing in future arms control discussions would address a genuine gap in the current framework.

The problem is that China has shown precisely zero interest in participating. Beijing has consistently argued that its arsenal is far smaller than those of Russia and the United States, that it maintains a no-first-use policy, and that the two superpowers should reduce their stockpiles dramatically before expecting China to join any limitations. Chinese officials have dismissed American overtures as attempts to constrain China's strategic modernization while maintaining American nuclear superiority.

Insisting on Chinese participation as a precondition for U.S.-Russian arms control is therefore a way of ensuring that no arms control happens at all. Whether this is the intended outcome or merely a convenient side effect depends on how charitably one interprets the Trump administration's nuclear policy.

What We Lose

The expiration of New START means more than just the end of numerical limits on deployed warheads. It means the end of verification. Under the treaty, American and Russian inspectors had the right to visit each other's nuclear facilities, count warheads, and confirm that both sides were complying with their commitments. These inspections had been suspended since Russia's 2023 announcement, but the legal framework for resuming them remained.

Now there is no framework. The United States and Russia are left to rely on national technical means, which is a euphemism for satellite imagery and signals intelligence, to assess each other's nuclear posture. These methods can detect large-scale changes but cannot provide the granular detail that on-site inspections offered.

Mike Albertson, who was involved in negotiating, ratifying, and implementing New START, warned that the Cold War was "full of examples where each side had preconceptions and assumptions about what the other side was doing, some of which was faulty and which led to expensive competitions on who was seen to be ahead or behind."

The risk is not immediate nuclear war. Neither Russia nor the United States is likely to dramatically expand its arsenal overnight. The risk is gradual erosion of stability, miscalculation based on incomplete information, and an eventual arms race that both sides insist they do not want but neither is willing to prevent.

Europe Watches Nervously

For European allies, the end of New START raises uncomfortable questions about the American nuclear umbrella that has protected the continent since the Cold War. NATO's deterrence doctrine assumes that the United States will use nuclear weapons, if necessary, to defend European allies from Russian aggression. That assumption becomes more complicated in a world where nuclear arsenals are unconstrained and nuclear postures are opaque.

The Netherlands, like other European NATO members, has no nuclear weapons of its own but hosts American nuclear bombs at Volkel Air Base under NATO's nuclear sharing arrangement. Dutch F-35 fighter jets are certified to deliver these weapons in a conflict scenario that everyone hopes will never occur.

The new Dutch government has committed to increasing defense spending to 3.5% of GDP, far above NATO's 2% target. Some of this spending will go toward conventional capabilities, but some will support the nuclear mission. In a post-New START world, that mission becomes both more important and more uncertain.

UN Secretary-General António Guterres issued a statement calling the treaty's expiration "a grave moment for international peace and security" and urging the United States and Russia to "immediately conclude a new nuclear arms control treaty." His words had approximately the same effect on the situation as previous UN statements on nuclear matters, which is to say none whatsoever.

The Long View

Nuclear arms control has always been an imperfect enterprise. The treaties negotiated during and after the Cold War did not eliminate the threat of nuclear war. They managed it, creating rules that made catastrophic miscalculation less likely and providing channels for communication that could function even when other aspects of the superpower relationship were hostile.

The architecture built over five decades, from SALT to START to New START, is now defunct. Nothing has replaced it. The two countries with the largest nuclear arsenals are once again operating without constraints, without verification, and without any formal obligation to discuss their nuclear posture with each other.

Axios reported on Thursday that American and Russian officials are "closing in on a deal to informally observe New START" limits beyond expiration, but that no agreement has been finalized. An informal understanding to continue doing what both sides were doing anyway is better than nothing, but it is a poor substitute for the legally binding, verified framework that just expired.

The Kremlin, for its part, indicated through spokesman Dmitry Peskov that Russia remains "ready for dialogue with the United States on limiting strategic offensive arms if Washington responds constructively." What constitutes a constructive response remains undefined, as does the timeline for any potential discussions.

A World Without Guardrails

In the meantime, both countries continue modernizing their nuclear forces. The United States is proceeding with new intercontinental ballistic missiles, a new strategic bomber, and new ballistic missile submarines. Russia is deploying new delivery systems including hypersonic weapons that were not covered by New START. China continues its expansion regardless of what Washington and Moscow do.

The world is not suddenly more dangerous than it was on February 4. But it is less transparent, less predictable, and less stable. The guardrails that generations of diplomats built to prevent nuclear catastrophe have been removed, and nobody is rushing to install new ones.

As one nuclear policy expert put it: "It's not like the arms race will begin on February 6th. But if we don't have any limitations and we don't have negotiations, both countries will plan for the worst case scenario."

Planning for the worst case scenario is how arms races begin. Whether this one can be prevented depends on decisions that no one in Washington, Moscow, or Beijing currently seems interested in making.