The Stockholm International Peace Research Institute (SIPRI) has released its Yearbook 2025, warning of an intensifying global arms race amid growing nuclear risks and a breakdown of existing arms control frameworks.
The annual publication, launched today, provides an authoritative assessment of developments in armaments, disarmament and international security, underscoring a sharp reversal in decades-long efforts to reduce nuclear arsenals.
According to SIPRI, nearly all nine nuclear-armed states continued modernising their arsenals in 2024, with signs of significant expansion. The total global inventory is now estimated at 12,241 nuclear warheads, of which 9614 are believed to be in military stockpiles. Approximately 3912 are deployed with missiles or aircraft, and 2100 are maintained at high operational alert—mainly by the United States and Russia, though China may have begun similar deployments 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 at 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.”
Russia and the United States still account for approximately 90 per cent of the world’s nuclear weapons. Although their respective stockpiles remained broadly stable in 2024, both countries are undertaking extensive modernisation programmes. These include the deployment of new warheads and enhanced delivery systems, suggesting potential growth in strategic arsenals if no successor to the 2010 New START treaty is agreed before its expiration in February 2026.
The US programme faced delays and budgetary pressures in 2024, particularly due to the cost implications of adding new non-strategic weapons. Russia also encountered setbacks, including test failures of its Sarmat intercontinental ballistic missile and slower-than-expected upgrades across other systems.
China’s nuclear expansion stands out as the most rapid among nuclear powers. SIPRI estimates its warhead stockpile reached at least 600 by January 2025—growing by around 100 warheads per year since 2023. Beijing has completed or is close to completing 350 new missile silos, signalling an ambition to rival the US and Russian ICBM force structure by 2030. However, even at a projected 1500 warheads by 2035, China’s arsenal would remain substantially smaller than those of the two largest powers.
The United Kingdom has not yet expanded its stockpile but is expected to do so following confirmation of plans to raise the cap on warhead numbers. The Labour government, elected in July 2024, has reiterated its intention to complete four new ballistic missile submarines and deliver further upgrades to the UK’s nuclear forces. Operational and fiscal constraints may, however, affect the implementation of these goals.
France advanced its own modernisation efforts during 2024, including development of a third-generation SSBN, a new air-launched cruise missile, and upgraded ballistic missiles. India and Pakistan both pursued new delivery systems, with India reportedly adopting canisterised missile technologies that may allow for the deployment of multiple warheads.
In early 2025, a brief armed confrontation between India and Pakistan highlighted the volatility of nuclear flashpoints. According to Matt Korda, Associate Senior Researcher at SIPRI, the incident involved strikes near nuclear-related sites and was accompanied by disinformation, raising the risk of escalation. “This should act as a stark warning for states seeking to increase their reliance on nuclear weapons,” Korda said.
North Korea is estimated to possess 50 assembled warheads and sufficient fissile material for 40 more. South Korean officials stated last year that Pyongyang was close to fielding a tactical nuclear weapon. In November 2024, North Korean leader Kim Jong Un called for the “limitless” expansion of the country’s programme.
Israel continues to refrain from publicly confirming its nuclear status, but SIPRI notes signs of modernisation, including a missile propulsion test and suspected upgrades at its Dimona reactor facility.
SIPRI Director Dan Smith, in his introduction to the Yearbook, warns that global arms control is entering a critical phase. With no successor talks underway for New START, and no indication of willingness to renew the bilateral treaty, the existing framework for strategic arms limitation may lapse entirely by early 2026. The insistence of US President Donald Trump on including China in future agreements further complicates prospects for negotiations.
Smith also highlights the transformative impact of emerging technologies—such as artificial intelligence, space-based systems, cyber tools, missile defences and quantum computing—on the strategic balance. These developments increase uncertainty and reduce transparency, creating new instability in an already fragile global environment.
“The idea of who is ahead in the arms race will be even more elusive and intangible than it was last time round,” Smith writes. “In this context, the old largely numerical formulas of arms control will no longer suffice.”
Beyond nuclear arsenals, the SIPRI Yearbook 2025 notes that debates about nuclear sharing and proliferation are intensifying. Russia claims to have deployed nuclear weapons in Belarus, while NATO member states are reviewing their hosting arrangements. French President Emmanuel Macron has reiterated calls for a European role in France’s deterrent.
The Yearbook also records wider geopolitical deterioration. The conflicts in Ukraine, Gaza and elsewhere have deepened global divisions. The election of President Trump has added uncertainty regarding the direction of US foreign and security policy, with implications for NATO, arms control and multilateral diplomacy.
Further information, including summaries and sample chapters, is available at www.sipriyearbook.org.
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