SIPRI Yearbook 2025 – Nuclear Weapons & Global Security: An Intelligence-Analytic Assessment

A dangerous new nuclear arms race is accelerating amid collapsing arms control regimes, rising geopolitical tensions, and destabilizing technologies. Given recent wars, there is an urgent need for multilateral restraint.

The Stockholm International Peace Research Institute (SIPRI) has released its 2025 Yearbook, presenting a detailed, data-driven evaluation of global armaments, disarmament efforts, and international security dynamics.

nuclear competition is entering a hazardous new phase, with outdated controls, unchecked arsenals, and rapidly evolving tech spawning new uncertainties
1. Strategic Warning: A New Nuclear Arms Race

SIPRI’s central finding is unambiguous: a new nuclear arms race is emerging amid the collapse of multilateral arms control regimes. The total global nuclear warhead inventory reached 12,241 by January 2025, down slightly, yet concealing a trend reversal in nuclear strategies. A key analytical insight: while the aggregate number remains stable, the deployment and modernization of nuclear capabilities are surging.

2. Operational Stockpiles & High Alert

Of this global arsenal, about 9,614 warheads are deployed for military use, with 2,100 on high operational alert, primarily under Russia and the U.S. Importantly, SIPRI notes China may now maintain some warheads on alert in peacetime—an observation signaling a shift toward doctrinal assertiveness.

3. Russia & USA: Modernization with Expansion Risk

Despite stable stockpile levels, Russia, with approx. 5,459 warheads, the U.S. with 5,177—both retain extensive modernization programmes. With the New START treaty set to expire in February 2026, and no viable replacement yet in negotiations, analysts assess a high likelihood of recklessly unchecked deployment. Potential triggers include:

• Strategic reloading of latent silo weapons in Russia,
• U.S. activation of dormant launchers and integration of new non-strategic systems targeting China.

4. China: The Fastest-Growing Nuclear Force

China’s nuclear arsenal is expanding at the fastest pace, with an estimated 600 warheads in early 2025 and an annual increase of ~100 warheads since 2023. Its construction of ~350 ICBM silos across strategic regions could enable near-parity with the U.S. or Russia by the decade’s end. Projections indicate potential growth to 1,000 warheads by 2030 and possibly 1,500 by 2035, though still below U.S./Russian levels.

5. Other Nuclear-Armed States—Incremental Modernization

• United Kingdom: Approved expansion in warhead ceiling (up to 260), with continued SSBN fleet upgrades.
• France: Ongoing third-generation SSBN and cruise missile upgrades, including enhanced warheads.
• India/Pakistan: Both are increasing arsenal capacity and delivery sophistication—India’s canister-launched missiles could host nuclear payloads in peacetime; Pakistan continues fissile stockpiling.
• North Korea: Estimated ~50 warheads, with materials for 40 more and advancing tactical nuclear capabilities.
• Israel: Though undeclared, developmental tests suggest modernization at Dimona.

6. Disarmament in Reversal

Since the Cold War’s end, disarmament progress has been driven by U.S.-Russian dismantlement programs. SIPRI cautions that this trend is reversing, as modernization overtakes the pace of dismantlement. Dan Smith, SIPRI Director, states:

“Bilateral nuclear arms control between Russia and the USA entered crisis some years ago and is now almost over.”

With New START both expired and unrenewed, and U.S. demands to include China further complicating talks, with “no sign” of diplomatic revival, strategic arms restraint is effectively nil.

7. Technology’s Role in Destabilization

Modern nuclear competition extends beyond sheer numbers. SIPRI flags the destabilizing potential of emerging technologies—AI, cyber systems, space tools, missile defense, and quantum tech—which threaten to revolutionize nuclear strategy. Automated decision-making, accelerated command systems, and digital vulnerabilities multiply the risks of miscalculation or accidental launches.

8. Proliferation & Nuclear Sharing Trends

SIPRI identifies renewed interest in nuclear sharing among allies. Belarus and Russia reaffirmed nuclear deployments in Belarus, while European NATO members have floated hosting U.S. weapons. France’s President Macron even proposed a “European dimension” to deterrence. SIPRI warns these steps may reduce national security, not enhance it.

9. Broader Security Context

The Yearbook situates nuclear developments within broader strategic fractures—the ongoing wars in Ukraine and Gaza, plus political uncertainty following the U.S. election of Donald Trump. These intersecting crises exacerbate geopolitical fragmentation and undermine confidence in traditional security architectures. 

Missing in the SIPRI Report

While SIPRI’s analysis offers a comprehensive overview of global nuclear dynamics, it notably omits a critical element of the current strategic landscape: the forward-deployment of U.S. nuclear weapons in Europe under NATO’s nuclear-sharing arrangements.

As of 2025, the United States is believed to store approximately 100 B61 nuclear bombs across air bases in Belgium, the Netherlands, Germany, Italy, and Turkey.

These tactical weapons, held in European territory but under U.S. control, are intended for potential use by dual-capable aircraft operated by host nations in coordination with NATO command.

The presence of these weapons continues to be a contentious issue—both within the host countries’ domestic politics and in broader discussions on strategic stability—especially as tensions with Russia intensify and public opinion in Europe becomes more skeptical of nuclear posturing.

Undemocratically, none of these countries has put the decision to host nuclear weapons on their territory to a vote by their lawmakers or subjected it to a public referendum. These decisions were typically made at the executive level within the context of NATO defense planning during the Cold War and continued through classified or non-transparent processes. Up to now, the citizens of these countries have not been consulted on the subject.

Moreover, their continued deployment raises legal and ethical concerns under the Treaty on the Non-Proliferation of Nuclear Weapons (NPT), which prohibits nuclear weapon states from transferring nuclear weapons to non-nuclear states. The strategic implications of these deployments—combined with calls from some NATO members to further expand nuclear sharing—underscore the fragile equilibrium of deterrence and the urgent need for renewed arms control dialogues that include NATO practices.

Israeli-Iran War

In light of the ongoing full-scale war between Israel and Iran—sparked by Israel’s unauthorized preemptive strikes on Iranian territory—the risk of nuclear escalation is no longer theoretical but dangerously plausible.

With sustained retaliatory attacks from Iran, mounting casualties, and key Israeli military installations under pressure, Israel may perceive an existential threat, especially if Iran gains explicit support from strategic allies such as Russia, China, or Pakistan.

In such a scenario, it could lead Israeli decision-makers to consider a tactical or demonstrative nuclear strike to neutralize Iranian capabilities or compel Iran to surrender.

Analytical Conclusions

1. The long era of nuclear reductions has ended, replaced by widespread modernization and renewed arms competition.
2. Major nuclear powers (U.S., Russia, China) are accelerating their arsenals, eroding long-standing strategic stability.
3. Multilateral arms control is in crisis, with New START nearing expiry, no successor in sight, and no incentive for broader inclusion (e.g., China).
4. Emerging technologies—AI, cyber tools, and space systems—are multiplying the risks of miscalculation and nuclear escalation.
5. Nuclear sharing and forward-deployment practices—such as U.S. warheads in Europe—are increasingly destabilizing, challenging non-proliferation norms and raising intra-alliance tensions.
6. The Israel–Iran war introduces the most immediate nuclear flashpoint, where a deteriorating Israeli military position could trigger the use of nuclear weapons under its doctrine of existential deterrence.
7. Crisis regions like the Middle East and South Asia are becoming nuclear tripwires, with asymmetric conflicts and disinformation adding volatility to fragile deterrence postures.

Implications for Decision-Makers:

• Urgent diplomatic action is needed to prevent a regional nuclear crisis, especially in the Middle East. Key actors must press for an immediate ceasefire and engage Israel and Iran through backchannels to re-establish red lines.
• NATO must reassess the strategic value and political cost of forward-deployed U.S. nuclear weapons in Europe, particularly as public opposition grows and tensions with Russia escalate.
• Reviving arms control must go beyond bilateral U.S.-Russia frameworks and account for rising powers like China and regional players like Israel, India, and Pakistan.
• New multilateral mechanisms must govern emerging nuclear-adjacent technologies, ensuring transparency and strategic stability amid rapid AI and cybermilitary developments.
• The current Israeli-Iranian war must serve as a warning, prompting the international community to urgently develop crisis containment protocols for nuclear-armed or nuclear-capable states involved in regional wars.

In conclusion, SIPRI Yearbook 2025 paints a stark picture: nuclear competition is entering a hazardous new phase, with outdated controls, unchecked arsenals, and rapidly evolving tech spawning new uncertainties. Failure to adapt multilateral norms now may lead to catastrophic consequences in the nuclear domain.

Ricardo Martins ‒PhD in Sociology, specializing in policies, European and world politics and geopolitics