A dangerous new nuclear arms race is emerging as disarmament efforts stall and nearly all nuclear-armed states expand and modernize their arsenals, according to the SIPRI Yearbook 2025, released today by the Stockholm International Peace Research Institute (SIPRI).
The report warns that the steady decline in global nuclear stockpiles since the end of the Cold War has come to a halt. In its place, a new era of expansion, modernization, and intensified nuclear rhetoric is taking hold, amid the collapse of arms control agreements and rising geopolitical tensions.
SIPRI estimates that as of January 2025, the global inventory of nuclear warheads stood at approximately 12,241, with 9,614 in military stockpiles available for use. Of those, 3,912 were deployed with missiles and aircraft, and around 2,100 were maintained on high operational alert—primarily by the United States and Russia. Notably, China may now also be keeping some warheads ready for launch during peacetime.
“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. “Instead, we see a clear trend of growing nuclear arsenals, sharpened nuclear rhetoric and the abandonment of arms control agreements.”
Russia and the United States still possess about 90 percent of all nuclear weapons worldwide. Although the size of their arsenals remained relatively stable in 2024, both countries are pressing forward with large-scale modernization programmes. In the absence of a new arms control agreement, SIPRI warns that both nations are likely to increase their deployed warhead numbers once the 2010 New START treaty expires in February 2026.
In the United States, modernization efforts in 2024 were hampered by planning and funding challenges, risking delays and escalating costs. The addition of new non-strategic nuclear weapons has further strained the programme. Meanwhile, Russia’s efforts faced setbacks, including a failed test of the Sarmat intercontinental ballistic missile and slower-than-expected upgrades. Still, both countries are positioned to increase their nuclear capabilities in the coming years by reactivating launchers, loading more warheads onto missiles, and modernizing delivery systems.
China’s nuclear expansion is the most rapid among the nine nuclear-armed states. SIPRI estimates that China now has over 600 warheads and is adding approximately 100 new warheads each year. By early 2025, it had completed or was close to completing around 350 new ICBM silos. If current trends continue, China could match the ICBM capacities of the U.S. and Russia by the end of the decade, though even a projected total of 1,500 warheads by 2035 would still represent just a third of current Russian or American stockpiles.
Other nuclear-armed states are also on the move. The United Kingdom is expected to expand its arsenal following a government commitment to continue building four new ballistic missile submarines and to upgrade existing systems, though significant financial and operational challenges remain. France continued developing a third-generation submarine and a new cruise missile, while also upgrading existing capabilities.
India and Pakistan both made advances in 2024. India’s development of “canisterized” missiles could allow for nuclear warheads to be deployed during peacetime, potentially with multiple warheads per missile. Pakistan continued to build new delivery systems and stockpile fissile material, indicating its arsenal may expand in the coming decade. Early 2025 saw tensions between the two countries escalate into armed conflict. Strikes on nuclear-related infrastructure and the spread of disinformation briefly raised the risk of nuclear confrontation.
“The combination of strikes on nuclear-related military infrastructure and third-party disinformation risked turning a conventional conflict into a nuclear crisis,” said Matt Korda, Associate Senior Researcher at SIPRI. “This should act as a stark warning for states seeking to increase their reliance on nuclear weapons.”
North Korea, meanwhile, continued to make its nuclear programme a central element of national security. SIPRI estimates it has assembled around 50 warheads and possesses enough fissile material to produce up to 40 more. South Korean officials reported in mid-2024 that the North was in the final stages of developing a tactical nuclear weapon. In November, Kim Jong Un called for a “limitless” expansion of the programme.
Israel, which does not officially confirm its nuclear status, is also believed to be modernizing its capabilities. In 2024 it tested a missile propulsion system likely linked to its Jericho ballistic missile family and appeared to upgrade the Dimona reactor site used for plutonium production.
SIPRI’s findings suggest a fundamental shift in the global nuclear landscape. With arms control frameworks eroding and modernization programmes advancing across all nuclear-armed states, the world appears to be entering a far more unstable and dangerous era—one in which the threat of nuclear conflict is rising, not receding.
