The world’s nine nuclear-armed states are upgrading and expanding their arsenals, accelerating an arms race that is creating “new risks” amid rising global tensions, a new report has warned.
Published on Monday, the study by the Stockholm International Peace Research Institute (SIPRI) said most of these countries deployed new nuclear-armed or nuclear-capable weapon systems last year.
It added that the powers’ increasing reliance on nuclear weapons is reversing decades of demobilisation efforts, even as dangers of escalation and miscalculation are growing.
“The evidence is growing that the nuclear weapon states are sidelining, and even walking away from, their disarmament commitments and are instead flexing their nuclear muscles,” said SIPRI researcher Hans Kristensen.
According to the SIPRI report, the nine nuclear powers – China, France, India, Israel, North Korea, Pakistan, Russia, the United Kingdom and the United States – possessed 12,187 nuclear warheads as of January this year, with some 9,745 of these held in military stockpiles for potential use.
The researchers said an estimated 4,012 warheads were deployed with missiles and aircraft, while up to 2,200 were kept on high alert, meaning they could be launched within minutes. Of these, nearly all belonged to Russia or the US, and to a lesser extent France and the UK.
Russia and the US remain the overwhelming nuclear powers, together possessing an estimated 83 percent of warheads available for military use and nearly 86 percent of all nuclear weapons globally.
While these figures are relatively on par with those from 2025, SIPRI said the countries’ “extensive” modernisation programmes “seem likely to increase the size and diversity of their arsenals in the future”.
The institute also said it expected the steady drop in the global nuclear stockpile that followed the end of the Cold War to be reversed in the coming years due to a slowdown in the dismantling of retired warheads by the leading powers and an acceleration in the deployment of new weapons.
SIPRI said China’s nuclear weapon arsenal – the world’s third largest – rose from about 600 warheads to 620 year-on-year, expanding faster than that of any other country.
The UK, on the other hand, is not believed to have increased its arsenal last year. But SIPRI said the country’s operational warhead stockpile is expected to increase in the future.
France, meanwhile, continued to modernise its capabilities as it announced plans to expand the number of warheads and said it would no longer publicly communicate the size of its arsenal.
SIPRI said India is thought to have once again slightly increased its nuclear arsenal in 2025. The country also continued development of new types of delivery systems, as did neighbouring Pakistan, which also continued to accumulate fissile material that could suggest a possible arsenal expansion in the coming years, the institute added.
Israel maintains its policy of nuclear ambiguity, but SIPRI estimates an arsenal of about 90 warheads. It is believed to be modernising its capabilities, while increased construction at the Negev Nuclear Research Center near Dimona in 2025 may signal broader long-term infrastructure upgrades.
Finally, North Korea is estimated to have possibly assembled a total of some 60 warheads, as the country continues to develop its capabilities to fulfil its stated goal of “exponentially” expanding its nuclear arsenal.
“Influential voices, including some world leaders, are advocating nuclear weapons as a guarantee against attack by a hostile state,” said SIPRI Director Karim Haggag.
“But making national defence and security strategies dependent – or more dependent – on nuclear weapons could significantly increase nuclear risks.”