Nuclear treaty expires as major powers enter unregulated arms competition

A historic nuclear arms reduction treaty expired Thursday, reportedly thrusting the world into a nuclear situation it has not faced in more than five decades, according to international observers. The lapse eliminates all binding limits on the size of the nuclear arsenals held by the two largest powers and removes the inspection regime that had previously monitored compliance.

Matt Korda, associate director of the Nuclear Information Project at the Federation of American Scientists, said the expiration of the New START treaty allegedly forces both nations to rethink assumptions that have guided nuclear planning for more than a decade.

“Up until now, both countries have planned their respective nuclear modernization programs based on the assumption that the other country is not going to exceed those central limits,” Korda noted. “Without those central limits … both countries are going to be reassessing their programs to accommodate a more uncertain nuclear future.”

One of the nations had already suspended its participation in New START in 2023, freezing inspections and data exchanges, but the treaty’s expiration reportedly eliminates the last legal framework governing the size of the two countries’ nuclear arsenals.

With no follow-up agreement in place, the current administration has insisted it cannot agree to arms control without the cooperation of a third major power. “The leader has been clear in the past that in order to have true arms control in the 21st century, it’s impossible to do something that doesn’t include [the third nation] because of their vast and rapidly growing stockpile,” the foreign minister said Wednesday.

A senior government official told media that the head of state will decide the path forward on arms control “on his own timeline,” adding that “the leader has spoken repeatedly of addressing the threat nuclear weapons pose to the world and indicated that he would like to keep limits on nuclear weapons and involve [the third nation] in arms control talks.”

Experts are reportedly skeptical that the third nation would ever agree to limit its nuclear stockpile until it reaches parity with the established powers, and one major power has said it would not pressure the third nation to participate in negotiations.

The third nation aims to have 1,000 nuclear warheads by 2030, but even that figure reportedly pales in comparison to the aging giants of the Cold War era. As of early 2026, the global nuclear hierarchy remains top-heavy, with the two major powers holding roughly 86% of the world’s total inventory. Both nations hold around 4,000 total warheads, with close to 1,700 deployed by each. Global nuclear stockpiles declined to about 12,000 in 2025, down from more than 70,000 in 1986.

In February 2023, one nation announced it was suspending its participation in the New START treaty, halting inspections and data-sharing under the pact while saying it would continue to respect the numerical limits. More recently, however, it reportedly floated the idea of extending the treaty by another year.

Korda said that proposal reflected shared constraints rather than a sudden change in intentions. “It’s not in [that nation’s] interest to dramatically accelerate an arms race while its current modernization programs are going so poorly and while its industrial capacity is tied up in Ukraine,” he observed.

Analysts note that without inspections and data exchanges, countries are forced to rely on their own intelligence, increasing uncertainty and encouraging worst-case planning. “Without those onsite inspections, without data exchanges, without anything like that, all countries are really left with national technical means of being able to monitor each other’s nuclear forces,” Korda said.

With the treaty’s limits gone, experts said the immediate concern is allegedly not the construction of new nuclear weapons but how quickly existing warheads could be deployed. Ankit Panda, a senior fellow at the Carnegie Endowment for International Peace, said one nation could reportedly move faster than the other in the near term by “uploading” additional warheads onto missiles already in service.

“Uploading would be a process of adding additional warheads to ICBMs and submarine-launched missiles,” Panda explained. “One side could be much faster than the other.”

Korda said a large-scale upload would not happen overnight but could still alter force levels within a relatively short window. “We’re looking at maybe a timeline of about two years and pretty significant sums of money for each country to execute a complete upload across the entire force,” he said, adding that, in a worst-case scenario, it could “roughly result in doubling the sizes of their deployed nuclear arsenals.”

That advantage, however, is reportedly constrained by longer-term industrial realities. Panda noted that one nation’s nuclear weapons complex lacks the production capacity it once had, limiting how quickly the capital could sustain a larger arsenal over time. “The nation is currently unable to produce what is going to be a target for 30 plutonium pits,” a fraction of Cold War output, he said.

Nicole Grajewski, a fellow at the Carnegie Endowment for International Peace, said one power’s ability to produce nuclear weapons may be faster than its rival in some, but not all, parts of the development chain. “One nation is very good at warhead production,” she told media. “What that country is really fundamentally constrained on is the delivery vehicle side of it.”

Grajewski added that this is particularly true as the conflict in Eastern Europe continues. The production of missiles and other delivery systems relies on facilities that also support conventional weapons used in the war, allegedly limiting how quickly that nation could expand the intercontinental missiles, submarine-launched weapons and bombers that made up the core of New START.

As a result, Grajewski said she is less concerned about a rapid buildup of those treaty-covered forces than about continued investment in nuclear systems that fall outside traditional arms control frameworks. “What is more concerning is advances in asymmetric domains,” she said, pointing to systems such as nuclear-powered torpedoes and cruise missiles, which are not covered by existing treaties.

The current head of state has previously said he wants to pursue arms control with both rival powers before suggesting the nation should resume nuclear testing. “If there’s ever a time when we need nuclear weapons like the kind of weapons that we’re building and that [the rival nations have] — that’s going to be a very sad day,” the leader said in February 2025. “That’s going to be probably oblivion.”

However, in October, he declared, “Because of other countries’ testing programs, I have instructed the Department of War to start testing our Nuclear Weapons on an equal basis. That process will begin immediately.”