A new report from the Stockholm International Peace Research Institute (SIPRI) warns that global nuclear weapons stockpiles are growing once again, reversing decades of gradual reductions.
The SIPRI Yearbook 2025, released this week, finds that nearly all nine nuclear-armed states are expanding or upgrading their arsenals, with China’s rapid buildup drawing particular attention.
According to SIPRI, an estimated 12,241 nuclear warheads exist globally as of January 2025. Of these, about 9,614 remain in military stockpiles and 3,912 are deployed with missiles or aircraft. Around 2,100 are on high operational alert—most of them held by Russia and the United States. Notably, SIPRI suggests China may now be keeping some warheads on missiles in 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 and Director of the Nuclear Information Project at the Federation of American Scientists. “Instead, we see a clear trend of growing nuclear arsenals, sharpened nuclear rhetoric and the abandonment of arms control agreements.”
China now has at least 600 warheads, SIPRI says, adding about 100 annually since 2023. Construction of approximately 350 new ICBM silos appears complete or near completion. The report states that depending on how China structures its force, it could match U.S. or Russian ICBM numbers by the early 2030s.
Russia and the U.S. continue to hold roughly 90 percent of the world’s nuclear weapons. Their respective modernization programs are well underway despite logistical and funding setbacks. Russia’s Sarmat ICBM program has faced delays, while the U.S. is encountering budgetary challenges that could disrupt future deployments.
SIPRI notes that unless a new treaty replaces the New START agreement—which expires in early 2026—the number of deployed U.S. and Russian strategic warheads is likely to rise.
“The signs are that a new arms race is gearing up that carries much more risk and uncertainty than the last one,” said SIPRI Director Dan Smith in the report’s introduction. Smith cited advances in artificial intelligence, quantum computing, and missile defense as contributors to instability in nuclear deterrence.
Other countries are also moving forward with nuclear modernization. France is developing new missile and submarine systems, the UK is increasing its warhead ceiling, and India and Pakistan are expanding delivery capabilities. North Korea now reportedly possesses around 50 assembled warheads, with enough fissile material for dozens more. In 2024, North Korean leader Kim Jong Un called for a “limitless” expansion of the country’s nuclear program.
SIPRI reports that Israel, which has not confirmed it holds nuclear weapons, is also modernizing its capabilities. This includes a propulsion test that may relate to the Jericho ballistic missile system and upgrades to the Dimona reactor.
The report underscores the broader erosion of arms control frameworks. With no replacement yet proposed for New START and no ongoing dialogue with Russia or China on future limitations, prospects for nuclear disarmament appear grim.
“The idea of who is ahead in the arms race will be even more elusive and intangible than it was last time round,” Smith said. “In this context, the old largely numerical formulas of arms control will no longer suffice.”
SIPRI also warns that increasing interest in nuclear-sharing arrangements and nuclear status in regions such as East Asia, the Middle East, and Europe could bring additional actors into the nuclear landscape.
“As the recent flare-up of hostilities in India and Pakistan amply demonstrated, nuclear weapons do not prevent conflict,” said Matt Korda, Associate Senior Researcher with SIPRI. “They come with immense risks of escalation and catastrophic miscalculation—particularly when disinformation is rife.”
The SIPRI Yearbook 2025 is published by Oxford University Press and remains a leading open-source reference on global nuclear trends and security dynamics.