The world’s nuclear-armed states are deepening efforts to modernize and expand their arsenals, reversing decades of gradual disarmament and raising alarms about a renewed nuclear arms race, according to a report released today by the Stockholm International Peace Research Institute (SIPRI). The analysis reveals that, after years of net reductions, the total number of operational warheads is once again on the rise, propelled by large-scale upgrade programs in the United States and Russia, rapid force expansion in China, and renewed weapons development in regional powers such as India, Pakistan and North Korea.
Scope and Significance of SIPRI Findings
SIPRI’s annual yearbook, a benchmark in global security research, reports that as of January 2025, the world possessed 12,241 nuclear warheads, of which 9,614 were in active stockpiles and ready for immediate use. While the total figure remains below Cold War peaks, it represents a discernible uptick over recent years. “After the end of the Cold War, warhead dismantlement outpaced new deployments,” explained SIPRI Director Dan Smith. “But that trend has stalled—and is now reversing in several key states.” His warning of emerging “dangerous and unstable” dynamics underscores the geopolitical tensions that have refocused attention on nuclear capabilities.
Major Nuclear Powers Ramp Up Modernization
United States
The U.S., holding roughly 5,428 warheads in stockpiles and 3,708 active, continues an ambitious modernization roadmap known as the Nuclear Posture Review. Over the past year, the Department of Defense and Department of Energy have accelerated development of a new land-based intercontinental ballistic missile (ICBM), the Ground-Based Strategic Deterrent (GBSD), set to replace the Minuteman III. The U.S. Navy’s Ohio-class ballistic missile submarines are being retrofitted with the Columbia-class SSBN, while the Air Force is upgrading its B-52 bomber fleet with the Long-Range Stand-Off (LRSO) cruise missile. In addition to delivery systems, the U.S. is investing in warhead life-extension programs (LEPs) to extend the service life of its existing W76 and W88 warheads into the 2080s.
Russia
Russia, accounting for approximately 5,977 total warheads and 1,588 operationally deployed, has similarly embarked on extensive upgrade programs. Moscow has unveiled new strategic systems such as the Avangard hypersonic glide vehicle, the Sarmat heavy ICBM, and the Poseidon nuclear-powered torpedo. Russian bomber forces are being equipped with the Kh-102 air-launched cruise missile, and silo-based ICBMs have received modernized warhead conversions. The Kremlin’s funding boost for its State Armaments Program 2024–2031 includes weapons of mass destruction, signaling that nuclear modernization remains a strategic priority alongside conventional capabilities.
China’s Rapid Arsenal Expansion
Although China’s arsenal remains modest by U.S.–Russian standards, SIPRI notes a rapid build-up from an estimated 500 warheads in 2022 to roughly 600 today. Data indicate that Beijing added approximately 100 new warheads in 2023 and 2024. China’s “reliable second-strike capability” is being strengthened through deployment of new silo fields in western provinces, development of road-mobile DF-41 ICBMs, and a burgeoning naval deterrent of ballistic missile submarines. “At its current pace, China could reach 1,000 warheads within seven to eight years,” Smith observed. “That would make China a much more prominent player in global nuclear politics.”
United Kingdom and France: Modernization without Expansion
The United Kingdom and France maintain smaller but advanced arsenals—approximately 225–260 warheads for the UK and around 290 for France. Though neither state appears to be increasing warhead numbers in 2024, both are executing comprehensive modernization plans. The UK’s Dreadnought-class SSBN will replace its Vanguard submarines, while France’s Barracuda-class SSBN and the upcoming generational update of its air-delivered ASMPA missiles keep its Triomphant fleet at the cutting edge. Both governments have legislated higher warhead ceilings—260 in London and 300 in Paris—suggesting flexibility to grow if political conditions shift.
Regional Powers and Proliferation Pressures
India and Pakistan
In South Asia, India and Pakistan continue to enhance their nuclear delivery systems. India’s stockpile of about 180 warheads is complemented by Agni-series ballistic missiles, naval deterrent vessels, and plans for strategic air-launched cruise missiles. Pakistan, holding an estimated 170 warheads, has expanded its aircraft-delivered stockpile and deployed the Hafeez short-range ballistic missile. Both countries are also developing tactical nuclear weapons with lower yields, raising concerns about “use-it-or-lose-it” doctrines in a regional crisis.
North Korea
North Korea’s isolated regime remains firmly committed to its nuclear and missile programs. SIPRI estimates 50 operational warheads with sufficient fissile material to reach 90. Pyongyang has tested intercontinental ballistic missiles (ICBMs) capable of reaching the U.S. mainland and continues high-profile nuclear tests. SIPRI warns that North Korea’s “nuclear weapons program remains central to its national security strategy,” with no sign of arms control diplomacy in sight.
Israel
Israel, which maintains a policy of nuclear opacity, is believed to have approximately 90 warheads, up from earlier offshore estimates. While Tel Aviv neither confirms nor denies its arsenal, intelligence assessments indicate ongoing modernization, including advanced air-delivered bombs and submarine-launched cruise missiles as part of its Dolphin-class fleet.
China’s Rise and the Shifting Balance
China’s projected growth to 1,000 warheads will still leave it well behind U.S. and Russian stockpiles, but the symbolic shift in strategic parity carries geopolitical weight. Smaller European powers, long anchored by U.S. extended deterrence, may reassess their own nuclear postures or seek stronger guarantees. Arms control agreements, such as New START—which caps deployed strategic warheads at 1,550 apiece for the U.S. and Russia—expire in 2026, raising the spectre of unconstrained competition.
The Technological Dimension: Beyond Warhead Counts
Dan Smith emphasizes that the coming arms race will be “highly technological,” spanning traditional delivery systems, space-based assets, cyberspace vulnerabilities, and artificial intelligence. Hypersonic weapons, satellite-based early warning, and AI-enhanced command-and-control systems alter the fabric of strategic stability. Smith warns that delegating launch decisions to AI poses existential risks: “Automating nuclear release protocols would take us perilously close to doomsday scenarios.”
Implications for Arms Control and Global Security
The resurgence of nuclear modernization undermines decades of arms control progress. Confidence-building measures, verification regimes, and multilateral treaties face renewed strain. Europe’s security architecture, shaken by the Russian invasion of Ukraine, contends with a nuclear-armed Russia on its doorstep. East Asia grapples with a more assertive China and North Korea’s provocations.
Renewed diplomacy could focus on extending and expanding New START, negotiating limits on non-strategic nuclear weapons, and addressing emerging domains such as space and cyberspace. However, SIPRI’s analysis suggests that without urgent political will, major powers will pursue divergent modernization paths, entrenching mutual suspicions and strategic competition.
Conclusion: A Call to De-Escalate
SIPRI’s 2025 data send a clear warning: the world stands at the threshold of a new nuclear arms race. As total warheads climb and advanced delivery systems proliferate, the margin for error—and for miscalculation—narrows. “We see the warning signs,” Dan Smith cautions. “Our geopolitical moment is volatile and dangerous.” Reversing this trend will require bold leadership, renewed arms control frameworks, and an international consensus that nuclear weapons ultimately threaten, rather than secure, human survival. The coming year will test whether states can step back from the precipice or hurtle toward a more unstable nuclear future.
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