SIPRI Yearbook 2025: A New Nuclear Arms Race Looms as Global Security Falters

New Delhi: The Stockholm International Peace Research Institute (SIPRI) released its 56th edition of the SIPRI Yearbook on June 16, 2025, delivering a sobering assessment of global armaments, disarmament, and international security. The report highlights the alarming emergence of a new nuclear arms race, driven by the modernization and expansion of nuclear arsenals among the nine nuclear-armed states: the United States, Russia, the United Kingdom, France, China, India, Pakistan, North Korea, and Israel. Coupled with a weakening of arms control regimes and rising geopolitical tensions, the findings underscore a world teetering on the edge of heightened nuclear risks and global instability.

Global Nuclear Stockpile Trends

According to SIPRI, the global inventory of nuclear warheads stood at an estimated 12,241 in January 2025, with 9,614 warheads in military stockpiles ready for potential use—an increase of approximately 29 warheads from the previous year. Of these, 3,912 were deployed on operational missile and aircraft systems, consistent with January 2024 figures, while the remainder were held in central storage. Notably, around 2,100 warheads were maintained on high operational alert on ballistic missiles, primarily owned by Russia and the United States, with indications that China may now keep some warheads on missiles during peacetime.

Since the end of the Cold War, the gradual dismantlement of retired warheads by Russia and the USA has typically outpaced new deployments, leading to a year-on-year decline in global nuclear stockpiles. However, SIPRI warns that this trend is likely to reverse, as the pace of dismantlement slows and new warhead deployments accelerate. Hans M. Kristensen, Associate Senior Fellow with SIPRI’s Weapons of Mass Destruction Programme and Director of the Nuclear Information Project at the Federation of American Scientists (FAS), stated, “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. Instead, we see a clear trend of growing nuclear arsenals, sharpened nuclear rhetoric, and the abandonment of arms control agreements.”

Nuclear Modernization Across Nations

All nine nuclear-armed states continued intensive modernization programs in 2024, upgrading existing weapons and introducing newer, more advanced systems. Below is a detailed breakdown of each country’s efforts:

• United States and Russia: Together, these nations hold approximately 90% of the world’s nuclear arsenal, with over 1,700 deployed warheads each and 4,521 in storage. Both are implementing extensive modernization programs that could increase the size and diversity of their arsenals. The U.S. faced planning and funding challenges in 2024, potentially delaying its strategic arsenal upgrades and increasing costs. The addition of new non-strategic nuclear weapons will further strain its modernization efforts. Russia encountered setbacks, including a test failure of its Sarmat intercontinental ballistic missile (ICBM) and delays in other system upgrades. Despite these challenges, both nations are poised to increase warhead deployments post-February 2026, when the New START treaty expires, unless a new agreement is reached.
• China: China’s nuclear arsenal is expanding faster than any other nation’s, reaching at least 600 warheads by January 2025, with an annual increase of about 100 warheads since 2023. The country has completed or is nearing completion of 350 new ICBM silos across northern deserts and eastern mountainous regions. By 2035, China could potentially match Russia or the USA in ICBM numbers, though its projected maximum of 1,500 warheads by 2035 would still be one-third of current U.S. and Russian stockpiles. China may also be developing a launch-on-warning capability, shifting from its no-first-use policy.
• United Kingdom: The UK’s nuclear stockpile, currently at 225 warheads, is set to grow to 260 following the 2023 Integrated Review Refresh. The Labour government, elected in July 2024, reaffirmed its commitment to building four new nuclear-powered ballistic missile submarines (SSBNs) to maintain continuous at-sea deterrence. However, operational and financial challenges loom large.
• France: France continued developing a third-generation SSBN and a new air-launched cruise missile in 2024, alongside refurbishing existing systems with improved ballistic missiles and new warhead modifications.
• India: India’s nuclear arsenal grew from 172 to 180 warheads in 2024, surpassing Pakistan’s 170. The country is developing “canisterized” missiles capable of carrying nuclear warheads during peacetime, potentially with multiple warheads per missile. India’s focus is shifting from Pakistan to include China, with longer-range missile development underway.
• Pakistan: Pakistan is accumulating fissile material and developing new delivery systems, suggesting its nuclear arsenal may expand over the next decade. It produces both highly enriched uranium (HEU) and plutonium for its weapons.
• North Korea: North Korea prioritizes its nuclear program, with an estimated 50 warheads and enough fissile material for up to 40 more. In July 2024, South Korean officials warned that North Korea was in the final stages of developing a tactical nuclear weapon. Leader Kim Jong Un called for a “limitless” expansion of the nuclear program in November 2024.
• Israel: Israel, which does not publicly acknowledge its nuclear arsenal, is modernizing its capabilities. In 2024, it tested a missile propulsion system potentially related to its Jericho family of nuclear-capable ballistic missiles and is upgrading its plutonium production reactor at Dimona.

Fissile Materials and Emerging Technologies

The explosive materials in nuclear weapons are fissile, either highly enriched uranium (HEU) or separated plutonium. China and Pakistan produce both, while India and Israel primarily use plutonium. The rapid development of technologies such as artificial intelligence (AI), cyber capabilities, space assets, missile defense, and quantum computing is redefining nuclear capabilities, deterrence, and defense. These advancements create potential sources of instability, particularly as AI accelerates decision-making in crises, heightening risks of miscommunication, misunderstanding, or technical accidents. Missile defense and oceanic quantum technology deployments could further impact the vulnerability of nuclear arsenals.

Arms Control in Crisis

The SIPRI Yearbook underscores a crisis in nuclear arms control. The New START treaty, the last remaining agreement limiting U.S. and Russian strategic nuclear forces, remains in force until February 2026, but there are no signs of negotiations to renew or replace it. U.S. President Donald J. Trump has insisted that any future deal include China, adding complexity to negotiations. SIPRI Director Dan Smith warns, “The signs are that a new arms race is gearing up that carries much more risk and uncertainty than the last one.” The decline of bilateral arms control and the absence of new agreements exacerbate these risks.

Key treaties aimed at curbing nuclear proliferation include:

• Treaty on the Non-Proliferation of Nuclear Weapons (NPT), 1970: The only binding treaty with a disarmament goal. India, Israel, and Pakistan never joined, and North Korea withdrew in 2003.
• Partial Test Ban Treaty, 1963: Bans nuclear tests in the atmosphere, outer space, and underwater. India signed and ratified.
• Comprehensive Nuclear Test Ban Treaty (CTBT), 1996: Bans all nuclear explosions. India did not sign.
• Treaty on the Prohibition of Nuclear Weapons (TPNW), 2017: Comprehensively prohibits nuclear weapon activities. India did not sign.
• New START Treaty, 2011: A bilateral treaty between Russia and the USA, set to expire in 2026.

In 2024, 178 countries ratified the CTBT, and four more ratified the TPNW, bringing its total to 73, with 25 others having signed but not ratified.

Regional Tensions and Nuclear Risks

Tensions between India and Pakistan escalated into armed conflict in early 2025, with strikes on nuclear-related infrastructure and third-party disinformation risking a nuclear crisis. Matt Korda, Associate Senior Researcher with SIPRI’s Weapons of Mass Destruction Programme, noted, “This should act as a stark warning for states seeking to increase their reliance on nuclear weapons.” In East Asia, Europe, and the Middle East, debates about nuclear status and strategy suggest potential for more states to develop or host nuclear weapons. Russia and Belarus claimed in 2024 that Russia deployed nuclear weapons on Belarusian soil, while several European NATO members expressed willingness to host U.S. nuclear weapons. French President Emmanuel Macron reiterated that France’s nuclear deterrent should have a “European dimension.”

Global Security Challenges

The SIPRI Yearbook also documents a broader deterioration in global security. Wars in Ukraine, Gaza, Myanmar, Sudan, and Ethiopia contributed to a rise in global conflict fatalities from 188,000 in 2023 to 239,000 in 2024. World military spending surged by 9.4% in 2024 to $2.7 trillion, a 37% increase over the past decade. The election of Donald Trump has introduced uncertainty about U.S. foreign policy, weakening its reliability as an ally and prompting European nations like Finland, Sweden, and Poland to sign agreements allowing U.S. troops and potentially nuclear weapons on their soil.

A Call for Caution

SIPRI’s findings paint a dire picture of a world on the cusp of a new nuclear arms race, driven by modernization, proliferation, and eroding arms control. Dan Smith emphasizes, “Eighty years into the nuclear era, it still makes absolutely no sense whatsoever to launch a nuclear war under any circumstances.” The combination of advanced technologies, rising conventional conflicts, and weakened deterrence frameworks underscores the urgent need for renewed global efforts to prevent nuclear escalation and restore stability.

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