The last remaining nuclear arms control treaty between the United States and Russia expires today, removing restrictions on the world’s two largest nuclear arsenals for the first time in decades and raising fears of a new, unrestricted arms race.
The Strategic Arms Limitation Treaty – known as New START – was signed in 2010 and was seen as a cornerstone of strategic stability, limiting the number of deployed strategic nuclear warheads and providing transparency measures designed to prevent miscalculations between Washington DC and Moscow.
What New START did—and why its expiration matters
New START limited the number of deployed strategic nuclear warheads for each side to 1,550. It also limited each side to no more than 700 deployed missiles and bombers and established mechanisms designed to reduce mistrust, including data transfers, notifications, and on-site inspections.
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These inspections were suspended in 2020 due to the COVID-19 pandemic and have never been resumed. In February 2023, President Vladimir Putin suspended Russia’s participation in the treaty amid escalating tensions over the war in Ukraine, although Moscow insisted it would continue to abide by the treaty’s main limits.
With the expiration of the treaty, the formal architecture that limited strategic nuclear deployments and ensured verification is to disappear entirely.
Putin’s Warning: A ‘More Dangerous’ World Without Limits
Russian officials have described the end of New START as destabilizing, even as Moscow signals it will now act as non-committal.
On Wednesday, the Russian Foreign Ministry said in a statement that “under the current circumstances, we assume that the parties to New START are no longer bound by any commitments or symmetrical declarations in the context of the treaty, including its basic provisions, and in principle can choose their next steps.”
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“At the same time, the Russian Federation intends to act in a responsible and balanced manner,” the statement said, adding that Moscow “remains ready to take decisive military-technical measures to counter potential additional threats to national security.”
Kremlin spokesman Dmitry Peskov said on Tuesday that it would be a “more dangerous” world without limits on US and Russian nuclear stockpiles.
Putin has previously argued that the expiration of the treaty could accelerate the proliferation of nuclear weapons and warned that the collapse of restrictions could encourage other states to seek nuclear weapons as a deterrent.
Trump’s stance: “If it expires, it expires… We’ll just make a better deal”
US President Donald Trump appears less concerned about the treaty’s expiration, even as Washington acknowledges the strategic risks.
Last month, Trump told the New York Times: “If it expires, it expires… We’ll just make a better deal”.
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A White House official said Monday that Trump has repeatedly indicated he would like to keep limits on nuclear weapons but wants China included in any future deal. Trump will make a decision on nuclear arms control “on his own timeline,” the official said.
Beijing has fought back by curbing its smaller — but rapidly expanding — nuclear arsenal. Moscow, meanwhile, has argued that any subsequent arrangement should also include France and the United Kingdom, Europe’s nuclear powers.
Pope Leo calls for renewal to avert a new arms race
With New START set to expire, international leaders have also called for renewed restraint.
Pope Leo on Wednesday urged the US and Russia to renew the treaty, saying the current world situation calls for “calls to do everything to prevent a new arms race”.
Collapse pattern: other arms control treaties are already gone
The expiration of New START follows the collapse of several major agreements that once supported European and global security.
- The Intermediate-Range Nuclear Forces Treaty, which largely eliminated the deployment of shorter-range nuclear weapons in Europe
- An open skies treaty that allowed signatories to conduct unarmed reconnaissance flights over the other side’s territory
- Treaty on Conventional Armed Forces in Europe, which limited the number of tanks, troops and artillery systems that Russia and NATO could deploy in Europe
The former head of Britain’s armed forces, Admiral Sir Tony Radakin, has warned the framework that has helped keep the world safe is “now in danger of falling apart”.
In a speech last year, he described the collapse of these key arms control treaties as “one of the most dangerous aspects of our global security today”, along with the “growing importance of nuclear weapons”.
Arms control experts warn of a three-way race involving China
Analysts say the end of New START removes predictability and increases incentives for worst-case planning — especially at a time when all three major nuclear powers are modernizing.
Daryl Kimball, executive director of the Arms Control Association in Washington, said: “We are now at a point where both sides could, after this treaty expires, for the first time in 35 years, increase the number of nuclear weapons that are deployed on each side.
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“And that would open up the possibility of an unlimited, dangerous three-way arms race, not just between the US and Russia, but also involving China, which is also expanding its smaller but still deadly nuclear arsenal.”
RAND Corporation’s Kingston Reif, a former US deputy assistant secretary of defense, warned during an online discussion that “in the absence of treaty predictability, each side could be motivated to plan for the worst, or to increase their deployed arsenals, to show toughness and resolve, or to seek negotiating leverage.”
Medvedev says end of contract should ‘worry everyone’
Russia’s Dmitry Medvedev – who signed New START as president in 2010 and is now deputy head of Putin’s Security Council – said its expiration should “concern everyone”.
Medvedev also issued a more explicit warning, saying Russia would respond strongly if faced with new threats.
Without agreements limiting its nuclear arsenal, Russia will “quickly and firmly repel any new threats to our security,” said Medvedev, who signed the New START treaty and is now the deputy head of Putin’s Security Council.
“If they don’t listen to us, we are acting appropriately to try to restore parity,” he said in recent remarks.
Golden Dome, hypersonic weapons and the race of new technologies
Experts say that the risk of an arms race is not only caused by politics, but also by technology.
Darya Dolzikova, senior researcher at the UK’s RUSI’s Proliferation and Nuclear Policy Programme, said the expiry of New START was “worrying because there are forces on both sides to expand their strategic capabilities”.
For Russia, she said, “there seems to be some concern about their ability to penetrate US air defenses” — concerns heightened by Trump’s plans to build a “Golden Dome” missile shield to protect North America from long-range weapons.
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Russia has developed systems designed to bypass missile defenses, including the Poseidon—an intercontinental, nuclear-armed, nuclear-powered underwater autonomous torpedo—and the Burevestnik, a nuclear-armed, nuclear-powered cruise missile.
The US, Russia and China are also developing long-range hypersonic missiles capable of maneuvering at speeds above 4,000 mph (6,437 km/h), making them difficult to intercept.
Dolzik said that these expanding capacities would “only make it more difficult” to negotiate a new arms control treaty.
New START in context: From the frontiers of the Cold War to today’s vacuum
New START followed decades of US-Soviet and later US-Russian arms control.
The original START treaty signed in 1991 between the US and the Soviet Union prohibited each side from deploying more than 6,000 nuclear warheads. Previously, SALT I in 1972 represented the first attempt to limit the arsenal of the superpowers.
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Other key pillars have since fallen away. The US withdrew from the 1972 Anti-Ballistic Missile Treaty in 2001. The Intermediate-Range Nuclear Forces Treaty – signed in 1987 – collapsed in 2019.
These developments left New START as the last remaining treaty limiting the two largest nuclear arsenals – until today.
What happens next: no rush to replace
Despite regular discussions, neither Washington nor Moscow appear to be close to signing a follow-up agreement.
The question reportedly came up when Putin met with Trump in Alaska last year, but no breakthrough followed. Putin said he was ready to continue to abide by New START limits for another year if Washington did the same, although Trump was noncommittal.
Rose Gottemoeller, the chief US negotiator for the pact and a former deputy secretary general of NATO, argued that the United States should have accepted the temporary extension.
“A one-year extension of New START’s limits would not jeopardize any of the major steps the United States is taking in response to the rise of China’s nuclear power,” she said in an online discussion last month.
Key things
- The expiration of New START marks the end of the critical U.S.-Russia nuclear arms control framework.
- The absence of a succession treaty increases the risk of an arms race, not only between the US and Russia, but also between China.
- International calls for renewed restraint highlight the urgent need for diplomatic efforts to prevent escalation.
