How the Expiration of the New START Treaty Rewrites the Rules of Global Nuclear Arms Control and Security

On February 5, 2026, the architecture of global nuclear restraint quietly collapsed. The New Strategic Arms Reduction Treaty (New START), the final bilateral pact limiting the nuclear arsenals of the United States and the Russian Federation, officially expired. Its lapse did not trigger an immediate crisis, but it marked the definitive end of an era. For the first time in more than half a century, the world's two largest nuclear powers are operating without any legally binding caps on their strategic forces or the intrusive verification mechanisms required to prove compliance.[1][5]

The expiration was not a surprise. Signed in 2010, New START was built with a hard expiration date. It allowed for exactly one five-year extension, which Washington and Moscow activated in February 2021. Once that clock ran out in 2026, the treaty could not be legally stretched further. While the diplomatic off-ramp was always to negotiate a successor agreement during that five-year grace period, geopolitical realities—specifically the war in Ukraine and the rise of China's nuclear program—ensured that no such negotiations took place.[1][5]

To understand what the world lost, it is necessary to look at what New START actually did. The treaty was not a disarmament pact; it was a management framework. It capped each side at 1,550 deployed strategic nuclear warheads and 700 deployed delivery vehicles, which include intercontinental ballistic missiles (ICBMs), submarine-launched ballistic missiles (SLBMs), and heavy bombers. It did not limit the thousands of non-deployed warheads sitting in storage, nor did it constrain shorter-range tactical nuclear weapons.[1][5]

But the numerical caps were arguably less important than the transparency regime that enforced them. New START mandated a constant stream of data exchanges between the two militaries, notifying each other whenever a missile was moved, a bomber was deployed, or a silo was upgraded. It also allowed for 18 short-notice, on-site inspections per year, where Russian inspectors could physically count warheads on American submarines, and vice versa. This system transformed nuclear deterrence from a guessing game into a verified mathematical equation.[2][4]

That transparency had already been eroding before the treaty's formal death. On-site inspections were initially paused in 2020 due to the COVID-19 pandemic. When the United States attempted to resume them in 2022, Russia refused. By February 2023, Moscow announced it was formally suspending its participation in the treaty's verification regime, though it pledged to continue abiding by the numerical caps. The 2026 expiration simply finalized the divorce, stripping away the legal obligation to maintain those caps.[3][5]

Without those caps, the immediate concern is the upload potential of both nations. Because New START only limited deployed warheads, both the US and Russia maintain total stockpiles of over 5,000 warheads each. If either side decides to maximize its strategic posture, it could rapidly pull warheads out of storage and attach them to existing delivery vehicles. Without inspectors to verify that a missile carries only one warhead instead of three, military planners are forced to assume the worst.[1][2]

This shift from verified parity to deterrence by estimation is the most dangerous consequence of the treaty's expiration. When a nation cannot definitively prove what its adversary is doing, it must plan for the maximum possible threat. If Washington suspects Moscow is uploading warheads, it faces immense pressure to do the same. This dynamic creates a classic security dilemma, where defensive hedging by one side is interpreted as an offensive buildup by the other, accelerating a silent arms race.[3][4]

Complicating this dynamic is the fact that the Cold War nuclear paradigm is obsolete. The bilateral framework of New START was designed for a world where only Washington and Moscow mattered. Today, the nuclear landscape is multipolar. China is engaged in a rapid expansion of its own nuclear forces, moving from a minimum deterrence posture to a robust, modern arsenal. The United States now faces what defense analysts call a two-peer nuclear challenge, requiring it to deter both Russia and China simultaneously.[2][3]

This multipolar reality is precisely why a successor to New START failed to materialize. The United States insisted that any future arms control framework must include China, arguing that bilateral caps are meaningless if a third party is allowed to build up unconstrained. Beijing, whose arsenal is still significantly smaller than those of the US and Russia, flatly refused to participate in limits that would lock in its numerical inferiority. Meanwhile, Russia demanded that the nuclear arsenals of NATO allies France and the United Kingdom be counted against the US total.[4][6]

With these incompatible demands deadlocking formal negotiations, the arms control community is being forced to rethink its entire approach. The era of grand, legally binding treaties capping warhead numbers may be over, at least for the foreseeable future. Instead, experts are pivoting toward more pragmatic, informal risk-reduction measures. If nations cannot agree on how many weapons to build, they might at least agree on how to prevent them from being used accidentally.[3][6]

These alternative frameworks focus on communication and behavior rather than arithmetic. Proposals include establishing dedicated crisis-communication hotlines between all nuclear-armed states, agreeing to mutual notifications for ballistic missile test launches, and creating rules of the road for how nuclear forces operate in close proximity. There is also a growing push to establish norms around emerging technologies, such as keeping artificial intelligence out of nuclear command-and-control systems.[3][4]

Despite the grim optics of the treaty's expiration, some defense analysts argue that strategic stability remains intact. Nuclear deterrence does not rely solely on treaties; it relies on the undeniable reality of mutually assured destruction. Both the United States and Russia possess massive, survivable second-strike capabilities. Even without New START's caps, neither side can launch a nuclear attack without guaranteeing its own annihilation. The fundamental physics of deterrence have not changed.[3][6]

However, relying purely on the fear of annihilation is a fragile strategy. Treaties like New START provided the guardrails that kept that fear manageable. They offered a shared vocabulary, a mechanism for resolving disputes, and a baseline of trust built through thousands of hours of joint inspections. Without those guardrails, the margin for error shrinks dramatically. A misread radar signal or a cyberattack on a command network is far more likely to escalate in an environment devoid of transparency.[2][4]

The expiration of New START also sends a chilling signal to the rest of the world. The core bargain of the 1968 Non-Proliferation Treaty (NPT) is that non-nuclear states agree never to build the bomb, provided the nuclear powers take steps toward disarmament. With the US and Russia abandoning their last bilateral constraint, non-nuclear states are increasingly frustrated. This dynamic threatens to weaken the global non-proliferation regime, potentially encouraging other nations to pursue their own nuclear deterrents.[1][4]

Ultimately, the end of New START forces a reckoning with the limits of technology and the necessity of diplomacy. While modern sensors and satellites can track missile silos from space, they cannot read the intentions of the leaders who control them. Arms control was never just about counting warheads; it was about managing the human fallibility that makes those warheads dangerous. As the world enters this unconstrained era, the challenge is no longer just reducing the numbers, but ensuring the system itself does not fail.[2][6]