Security and public safety
Understand UK terrorism threat levels
UK terrorism threat levels describe the assessed likelihood of an attack. They help security professionals decide protective measures and give the public context. This guide explains the categories without displaying a live status. Check MI5 for the current assessment, and follow police instructions about any incident affecting your area.
Published: Updated:
Last checked: 7 November 2026 How we evaluate sources
What the five levels mean
Each label describes the likelihood of a terrorist attack. It does not predict an exact time or location.
| Level | Likelihood of an attack |
|---|---|
| Low | Highly unlikely |
| Moderate | Possible, but unlikely |
| Substantial | Likely |
| Severe | Highly likely |
| Critical | Highly likely in the near future |
Use the right assessment
MI5 publishes the national terrorism assessment and a separate assessment for Northern Ireland-related terrorism in Northern Ireland. Read the scope shown alongside each one. A UK assessment should not be used to judge travel risks overseas; use the destination's FCDO advice instead.
Threat levels are reviewed as information changes. A change does not, by itself, necessarily require the public to take a particular action. Local police advice, an emergency alert or a venue instruction may give you specific steps relevant to your situation.
A practical awareness checklist
For a business or event, national threat levels are one input to protective planning. Site response arrangements also depend on the premises and its specific risks. Staff should follow their organisation's procedures.
- Use the MI5 page when checking a claim that the level has changed.
- Follow your local police force for verified information about an incident.
- Notice exits and follow staff instructions in stations, shops and public venues.
- Know the emergency arrangements at your workplace or regular venue.
- Agree how your household would contact each other if transport or phones were disrupted.
- Check information before sharing it, including its date and location.
Report a concern safely
Report information that could relate to terrorism through the police reporting route or the confidential anti-terrorist hotline, 0800 789 321. Use 999 for an immediate threat.
Explain what you actually saw or heard, where and when it happened, and any useful detail. Let the police assess the information. Do not confront someone, investigate them yourself or publish accusations. Focus on concerning behaviour and facts rather than a person's appearance or background.
Counter Terrorism Policing: report suspicious activity (opens in a new tab)
Know Run Hide Tell
For a firearms or weapons attack, escape if a safe route is available. Leave possessions behind. If escape is unsafe, hide, secure your position where possible and silence your phone, including vibration. Call 999 when it is safe and follow the call handler's instructions.
Read the full police guidance in advance. During an incident, do not delay to film events or return towards danger to collect belongings.
Read Counter Terrorism Policing’s Run Hide Tell guidance (opens in a new tab)
Common questions
Is this page showing the current threat level?
No. It explains the categories. Use the linked MI5 page for the current published assessments and their scope.
Does a higher level mean I must cancel ordinary activities?
A level change does not automatically require a specific public response. Check for police, organiser or transport instructions affecting your actual plans.
Make your next step practical
Keep preparing
Evidence and service information
Sources behind this guidance
We develop our guidance using the sources below. Check the named organisation for current service details, live warnings and local instructions. Sources checked 7 November 2026.
- Threat levelsMI5
- Threat and response levelsProtectUK
- Report suspicious activityProtectUK / Counter Terrorism Policing
- Run Hide TellProtectUK / Counter Terrorism Policing