Nuclear miscalculation not involving the UK

Impact 5
upper risk error bar
upper likelihood error bar
risk indicator
lower likelihood error bar
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ID 63
Risk theme Conflict and instability
Impact & Likelihood
Impact key
5 Catastrophic
4 Significant
3 Moderate
2 Limited
1 Minor
Likelihood key
5 >25%
4 5-25%
3 1-5%
2 0.2-1%
1 <0.2%


Some countries possess nuclear weapons, so this will always remain a risk. Nuclear miscalculation refers to the risk that a state will mistakenly understand the intentions of another state and respond by launching a nuclear strike. The false belief that an attack is imminent causes a country to ‘miscalculate’ the risk of full-scale war and escalate a conflict to the nuclear level.

The UK works within the Non-Proliferation Treaty to stop the spread of nuclear weapons, promote cooperation and advance nuclear disarmament. The UK does everything it can to promote diplomatic solutions to every conflict.


The reasonable worst-case scenario for this risk involves a limited nuclear conflict between two states that does not involve the UK. The impacts in the affected region would be catastrophic, particularly in terms of numbers of casualties and fatalities. There would be famine as a result of the event (caused from the fallout and the impact on the climate affecting food production). This would increase demand for imported foods leading to a dramatic increase in the cost of basic and staple foods in the UK. The human and economic impact of the event would necessitate enormous long-term humanitarian assistance. There would be implications for UK businesses with direct or indirect ties to the affected region. British Nationals in the region would require support. There would be the potential for high levels of migration to the UK, increasing pressure on infrastructure.

Response capability requirements

The UK maintains a civilian staff qualified to monitor radiation levels. Humanitarian assistance would be provided and our border staff would prepare to handle higher numbers of refugees needing assistance.


The extent of the recovery needed for the UK would depend on the scale of the secondary impacts. Recovery in the affected areas would take many years and large-scale investment would be required.