The last remaining bilateral treaty between the United States and Russia limiting strategic nuclear arms expires on Thursday, leaving the two countries with no control over their nuclear arsenals.
The New Strategic Arms Reduction Treaty (New START) was signed in 2010 by US President Barack Obama and his Russian counterpart, Dmitry Medvedev.
Under its provisions, the two countries committed to reducing strategic nuclear forces and opened the door to extensive on-site inspections to verify compliance.
The pact between Washington and Moscow, formally known as the Treaty on Measures for the Further Reduction and Limitation of Strategic Offensive Arms, restricted each side to no more than 1,550 nuclear warheads on no more than 700 missiles and bombers — deployed and ready for use.
It was originally supposed to expire in 2021 but was extended for five more years.
The pact also envisioned sweeping on-site inspections to verify compliance, but these ended in 2020 due to the COVID-19 pandemic and never resumed.
In February 2023, Russian President Vladimir Putin suspended Moscow’s participation, saying the Kremlin could not allow US inspections of its nuclear sites at a time when Washington and its NATO allies have openly declared Moscow’s defeat in Ukraine as their goal.
At the same time, the Kremlin emphasised it was not withdrawing from the pact altogether, pledging to respect its caps on nuclear weapons.
In September 2025 Putin again declared his readiness to adhere to nuclear arms limits for one more year and urged Washington to follow suit.
He even said that allowing the New START agreement to expire would be “destabilising” and could fuel the proliferation of nuclear weapons.
“To avoid provoking a further strategic arms race and to ensure an acceptable level of predictability and restraint, we believe it is justified to try to maintain the status quo established by the New START Treaty during the current, rather turbulent period,” Putin stated amid Moscow’s numerous threats to use tactical nuclear weapons against NATO countries in the backdrop of Russia’s war against Ukraine.
Obama, who signed the New START while in office, said its expiration “would pointlessly wipe out decades of diplomacy, and could spark another arms race that makes the world less safe”.
Nine out of 10 nukes in the arms of Russia and US
Russia and the US together possess around 90% of all nuclear weapons.
Both countries are implementing extensive modernisation programmes to all three legs of their nuclear triads (land, sea, and air) that could increase the size and diversity of their arsenals in the future.
Putin has repeatedly threatened to use nuclear weapons against Ukraine since the beginning of Moscow’s full-scale invasion in 2022, saying he was prepared to use “all means” to protect its security interests.
In 2024, he also signed a revised nuclear doctrine lowering the threshold for nuclear weapons use.
In November 2024 and then in January of this year, Russia attacked Ukraine with a conventional version of its new Oreshnik intermediate-range ballistic missile.
Moscow says its hypersonic missile has a range of up to 5,000 kilometres, capable of reaching any European target, with either nuclear or conventional warheads.
In October 2025 Russia claimed it conducted a successful test of a new nuclear-powered and nuclear-capable underwater drone, known as Poseidon.
Putin said it "cannot be intercepted,” stating the drone has already been dubbed a "doomsday machine".
Around the same time US President Donald Trump alluded to Washington’s plans to resume underground nuclear detonation tests.
“We’re going to do some testing,” Trump said. “Other countries do it. If they’re going to do it, we’re going to.” The US president did not offer more details.
The US has been investing heavily in modernising its nuclear arsenal, including Sentinel, the US Air Force's next-generation intercontinental ballistic and missile and B-21, long-range stealth strategic bombers designed to penetrate advanced air defences and carry both conventional and nuclear weapons.
Just days after returning to the White House in January last year, Trump unveiled his intentions for the multilayered system, aimed at countering "next-generation" aerial threats to the US, including ballistic and cruise missiles.
The future Golden Dome defence programme for the first time will put US weapons in space and will be “fully operational” before the end of Trump’s term, he said.
New kid on the block
China was never party to any of the nuclear arms control agreements, in the Cold War or after, but it has more than doubled its arsenal over the past decade.
Beijing has a considerably smaller arsenal of 600 warheads, very few of which are deployed and ready for use, according to the Federation of American Scientists (FAS).
By comparison the FAS assesses the US arsenal at 5,177, including stockpiled and retired warheads, and Russia’s at 5,459.
But China’s nuclear arsenal is growing faster than any other country’s, by about 100 new warheads a year since 2023, according to the Stockholm International Peace Research Institute.
“Depending on how it decides to structure its forces, China could potentially have at least as many ICBMs as either Russia or the USA by the turn of the decade”, SIPRI said.
Last year Trump said that he wanted China to be part of arms control and questioned why the US and Russia should build new nuclear weapons given that they had enough to destroy the world many times over.
“If there's ever a time when we need nuclear weapons like the kind of weapons that we're building and that Russia has and that China has to a lesser extent but will have, that's going to be a very sad day,” he said in February last year.
“That's going to be probably oblivion.”
On Wednesday, just hours before the New START treaty between Washington and Moscow was set to expire, US Secretary of State Marco Rubio reiterated that any nuclear deal with Russia must include China.
"The president (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 China, because of their vast and rapidly growing stockpile," Rubio told reporters.
Beijing rejected the idea of being part of any new treaty. "China’s position on a trilateral negotiation with the US and Russia on nuclear arms control is clear," Chinese Foreign Ministry spokesperson Lin Jian said.
"China’s nuclear strength is by no means at the same level with that of the US. It is neither fair nor reasonable to ask China to join the nuclear disarmament negotiations at this stage," he stated.
Instead Beijing called for all nuclear powers to adopt a no-first-use policy, a commitment to never initiate nuclear warfare, reserving such weapons solely to retaliate against a nuclear attack. Both Washington and Moscow have dismissed the calls.
European nuclear powers
In response, Russia said the nuclear forces of NATO members, the UK and France, should also be up for negotiation, which those countries reject, especially since Russia’s full-scale invasion of Ukraine.
France has the largest nuclear arsenal in Europe with 290 weapons - almost all of them combat-ready.
In October 2025 Paris introduced a modernised version of its M51 submarine-launched strategic ballistic missile, a “major milestone” in the development of the country’s ocean-based nuclear deterrent, the French Armed Forces Ministry said.
The third and latest version of the M51 has new nuclear warheads as well as improved range, accuracy and capability to penetrate enemy defences, the ministry said in an emailed statement.
The UK, with fewer than 250 warheads, has also committed to scaling up its maritime nuclear capabilities by building four new nuclear-powered ballistic missile submarines.
In July of last year, France and the UK announced the Northwood Declaration, a landmark accord that expands the scope of bilateral nuclear cooperation to an unprecedented degree.
The two countries committed not only to deepening technical and policy dialogue but also to exploring the coordination of their nuclear forces.
While preserving national decision-making, the declaration signals for the first time that Paris and London are prepared to align their strategic postures in new ways to counter major nuclear and non-nuclear threats to Europe.
