World entering new era as nuclear powers build up arsenals, says SIPRI
Of the total global inventory of an estimated 12,241 warheads in January 2025, about 9,614 were in military stockpiles for potential use, the Stockholm International Peace Research Institute said in its yearbook
Highlights:
- Nuclear states are modernising arsenal
- Russia and US hold 90% of nuclear warheads
- China's nuclear arsenal growing the fastest
- More states considering developing or hosting nuclear weapons
The world's nuclear-armed states are beefing up their atomic arsenals and walking out of arms control pacts, creating a new era of threat that has brought an end to decades of reductions in stockpiles since the Cold War, a think tank said on Monday.
Of the total global inventory of an estimated 12,241 warheads in January 2025, about 9,614 were in military stockpiles for potential use, the Stockholm International Peace Research Institute (SIPRI) said in its yearbook, an annual inventory of the world's most dangerous weapons.
Around 2,100 of the deployed warheads were kept in a state of high operational alert on ballistic missiles, nearly all belonging to either the US or Russia.
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SIPRI said global tensions had seen the nine nuclear states - the United States, Russia, the United Kingdom, France, China, India, Pakistan, North Korea and Israel - plan to increase their stockpiles, reports Reuters.
Since the end of the cold war, the gradual dismantlement of retired warheads by Russia and the US has normally outstripped the deployment of new warheads, resulting in an overall year-on-year decrease in the global inventory of nuclear weapons. This trend is likely to be reversed in the coming years, as the pace of dismantlement is slowing, while the deployment of new nuclear weapons is accelerating.
"The era of reductions in the number of nuclear weapons in the world, which had lasted since the end of the cold war, is coming to an end," said Hans M Kristensen, associate senior fellow with SIPRI's Weapons of Mass Destruction Programme and director of the Nuclear Information Project at the Federation of American Scientists (FAS). "Instead, we see a clear trend of growing nuclear arsenals, sharpened nuclear rhetoric and the abandonment of arms control agreements."
SIPRI said Russia and the US, which together possess around 90% of all nuclear weapons, had kept the sizes of their respective usable warheads relatively stable in 2024. But both were implementing extensive modernisation programmes that could increase the size of their arsenals in the future.
The fastest-growing arsenal is China's, with Beijing adding about 100 new warheads per year since 2023. China could potentially have at least as many intercontinental ballistic missiles as either Russia or the US by the turn of the decade.
According to the estimates, Russia and the US held around 5,459 and 5,177 nuclear warheads respectively, while China had around 600.
India is believed to have once again slightly expanded its nuclear arsenal in 2024 and continued to develop new types of nuclear delivery system. India's new "canisterised" missiles, which can be transported with mated warheads, may be capable of carrying nuclear warheads during peacetime, and possibly even multiple warheads on each missile, once they become operational.
Pakistan also continued to develop new delivery systems and accumulate fissile material in 2024, suggesting that its nuclear arsenal might expand over the coming decade.
Arms control in crisis amid new arms race
In his introduction to SIPRI Yearbook 2025, SIPRI Director Dan Smith warns about the challenges facing nuclear arms control and the prospects of a new nuclear arms race.
Smith observes that "bilateral nuclear arms control between Russia and the US entered crisis some years ago and is now almost over". While New START—the last remaining nuclear arms control treaty limiting Russian and US strategic nuclear forces—remains in force until early 2026, there are no signs of negotiations to renew or replace it, or that either side wants to do so.
US President Donald J Trump insisted during his first term and has now repeated that any future deal should also include limits on China's nuclear arsenal—something that would add a new layer of complexity to already difficult negotiations.
More states considering developing or hosting nuclear weapons
Revitalised national debates in East Asia, Europe and the Middle East about nuclear status and strategy suggest there is some potential for more states to develop their own nuclear weapons.
In addition, there has been renewed attention on nuclear-sharing arrangements. In 2024 both Belarus and Russia repeated their claims that Russia has deployed nuclear weapons on Belarusian territory, while several European NATO members signalled their willingness to host US nuclear weapons on their soil, and France's President Emmanuel Macron repeated statements that France's nuclear deterrent should have a 'European dimension'.
"It is critical to remember that nuclear weapons do not guarantee security," said Matt Korda, associate senior researcher with SIPRI's Weapons of Mass Destruction Programme and Associate Director for the Nuclear Information Project at FAS.
"As the recent flare-up of hostilities in India and Pakistan amply demonstrated, nuclear weapons do not prevent conflict. They also come with immense risks of escalation and catastrophic miscalculation—particularly when disinformation is rife—and may end up making a country's population less safe, not more."
