In Depth
Why are nuclear weapons still a global risk?
Deterrence can reduce some risks and create others: error, escalation and new technologies remain open problems.
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In Brief
- According to the SIPRI Yearbook 2026, nine states possess nuclear weapons and the global inventory is estimated at about 12,187 warheads as of January 2026.
- Of these, about 9,745 are in military stockpiles for potential use and about 4,012 are deployed; between 2,100 and 2,200 are deployed in a state of high alert on ballistic missiles.
- In 2025 nuclear-armed states continued to modernise their arsenals.
- SIPRI reports a growing centrality of nuclear weapons in security strategies and an increase in the risks of error and escalation.
What we know
Documented facts
- Existing nuclear arsenals are documented and estimated annually: the figures above come from the SIPRI Yearbook 2026.
- A significant portion of deployed warheads are in a state of high alert, meaning ready for use within a very short time.
- Modernization programs cover delivery systems, warheads and command-and-control systems in all nuclear-armed states.
- SIPRI's analysis on multidomain escalation risk describes how cyber, space, advanced conventional systems and artificial intelligence can interact with the nuclear dimension.
How sure are we?
Solid evidence
Numerous studies and authoritative sources converge.
The evidence is solid on the size of arsenals, alert status and modernization programs. Whether and how much deterrence reduces or increases overall risk is instead the subject of a real debate among experts: we present it as such, not as a settled question.
Different arguments and positions
Deterrence reduces risk
- The prospect of catastrophic consequences would discourage a direct attack between powers.
- Arsenals would guarantee a stability, however precarious, among adversaries.
Deterrence shifts and amplifies risk
- Stability depends on human decisions, accurate information and technical systems that can fail.
- Very short decision times and high alert leave little room to correct an error.
- New technological domains can create ambiguity and unforeseen escalation pathways.
What the evidence shows
The sources document arsenals, alert status and escalation dynamics. They do not provide a shared measure of overall risk: on this, the debate among experts remains open.
What we don't know
- It is not possible to reliably quantify the probability of nuclear use, whether intentional or accidental.
- We do not know precisely how automated and decision-support systems will affect the timing and quality of decisions in a crisis.
- Information on some arsenals is partial: estimates depend on open sources and official declarations with uneven transparency.
Why it matters
- It is one of the few risks capable of producing irreversible consequences on a global scale in a very short time.
- The resources absorbed by arsenal modernization compete with other collective needs.
- Managing nuclear risk is a test of states' ability to cooperate on truly global issues.
What we can do
- Distinguish the long-term goal — reducing nuclear risk to the point of elimination — from measures that can be applied right away.
- Support immediate tools: crisis communication channels, treaties and verification mechanisms, reducing alert status, arms control, escalation prevention.
- Ask for greater transparency on data regarding arsenals and doctrines.
The No-Extinction proposal
Proposals
- No-Extinction proposes treating nuclear risk reduction as a priority global competence, with independent verification and shared rules on the interaction between automated systems and use decisions.
Sources and data
The links lead to the original documents and open in a new tab. Every figure cited in this article comes from these sources.
SIPRI
SIPRI Yearbook 2026 — data on world nuclear forces
yearbook and press release · 2026
www.sipri.org/media/press-release/2026/increasing-focus-nuclear-weapons-amid-heightened-escalation-risks-new-sipri-yearbook-out-now(opens in a new tab)SIPRI
Addressing Multidomain Nuclear Escalation Risk
policy report · 2026
www.sipri.org/publications/2026/policy-reports/addressing-multidomain-nuclear-escalation-risk(opens in a new tab)