Major nuclear-weapon states continued to modernize their arsenals last year, paving the way for a new nuclear arms race, the Stockholm International Peace Research Institute (SIPRI) warned in a report released today.
Nuclear powers, particularly the US and Russia, which account for around 90 percent of the world's stockpiles, have begun to "modernize existing weapons and add new versions," the SIPRI report said.
Since the end of the Cold War, older warheads have generally been dismantled faster than new ones have been deployed, leading to a reduction in the total number of warheads.
That trend will likely reverse in the coming years.
"What we see today, first of all, is that the number of operational nuclear warheads is starting to grow again," SIPRI director Dan Smith told AFP.
This is particularly the case with China, which, according to SIPRI estimates, possesses around 600 nuclear warheads, after adding 100 new warheads each year during 2023 and 2024.
"China is steadily increasing its nuclear force," Smith said, adding that "it is possible to reach 1.000 warheads within seven or eight years."
While that number is still far from the Russian and American arsenals, it will make China a "much stronger player," Smith said.
The world is facing new threats "in a particularly dangerous and unstable time" for geopolitics, he added, adding that signs of a "new nuclear arms race" are emerging.
SIPRI identified a total of 12.241 warheads in January 2025, including 9.614 stockpiled for potential use.
Russia and the US have "extensive nuclear warhead modernization and replacement programs," the report said.
The UK did not increase the number of warheads in 2024, but given the country's decision in 2021 to increase the warhead limit from 225 to 260, that number is likely to increase in the future, the institute said.
Similarly, France has about 290 warheads, but its nuclear weapons modernization program advanced during 2024. India and Pakistan "continued to develop new types of nuclear weapon delivery systems in 2024." By early 2025, India had a growing stockpile of approximately 180 nuclear weapons, while Pakistan's arsenal remained stable at about 170 warheads, the report said.
North Korea's nuclear weapons program remains "central to its national security strategy," the report added. SIPRI estimates its arsenal at around 50 warheads and believes the country has "sufficient fissile material to reach a total of up to 90 warheads."
Israel, which does not admit to possessing nuclear weapons, is also reportedly modernizing its arsenal, which SIPRI estimated at the beginning of the year contained approximately 90 warheads.
The upcoming nuclear arms race is not just about the number of warheads, Smith said, adding that there is a high-tech arms race that will take place in both "space and cyberspace," as the software for controlling and guiding nuclear weapons will be a competitive area.
The rapid development of artificial intelligence is likely to play a role, initially as a complement to humans.
"The next step would be to move to full automation. That's a step we should never take," Smith said.
"If our chances of escaping the danger of nuclear war were left in the hands of artificial intelligence, I think we would be close to the worst-case scenario," the SIPRI director added.
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