Members of the public should always remain alert to the danger of terrorism and report any suspicious activity to the police on 999 or the anti-terrorist hotline: 0800 789 321. If your information does not relate to an imminent threat, you can also contact MI5.

Current national threat level

The threat to the UK (England, Wales, Scotland and Northern Ireland) from terrorism is SUBSTANTIAL.

Current Northern Ireland-related terrorism threat level

The threat to Northern Ireland from Northern Ireland-related terrorism is SEVERE.

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What the threat levels mean

Threat levels are designed to give a broad indication of the likelihood of a terrorist attack.

LOW means an attack is highly unlikely

MODERATE means an attack is possible, but not likely

SUBSTANTIAL means an attack is likely

SEVERE means an attack is highly likely

CRITICAL means an attack is highly likely in the near future

How are threat levels decided?

The threat level for the UK from international terrorism is set by the Joint Terrorism Analysis Centre (JTAC).

MI5 is responsible for setting the threat levels from Irish and other domestic terrorism both in Northern Ireland and in Great Britain.

In reaching a judgement on the appropriate threat level in any given circumstance several factors need to be taken into account.

These include:

Available intelligence. It is rare that specific threat information is available and can be relied upon. More often, judgements about the threat will be based on a wide range of information, which is often fragmentary, including the level and nature of current terrorist activity, comparison with events in other countries and previous attacks. Intelligence is only ever likely to reveal part of the picture.

Terrorist capability. An examination of what is known about the capabilities of the terrorists in question and the method they may use based on previous attacks or from intelligence. This would also analyse the potential scale of the attack.

Terrorist intentions. Using intelligence and publicly available information to examine the overall aims of the terrorists and the ways they may achieve them including what sort of targets they would consider attacking.

Timescale. The threat level expresses the likelihood of an attack in the near term. We know from past incidents that some attacks take years to plan, while others are put together more quickly. In the absence of specific intelligence, a judgement will need to be made about how close an attack might be to fruition. Threat levels do not have any set expiry date, but are regularly subject to review in order to ensure that they remain current.

How should you respond?

Threat levels in themselves do not require specific responses from the public. They are a tool for security practitioners working across different sectors of the Critical National Infrastructure (CNI) and the police to use in determining what protective security response may be required.

Vigilance is vital regardless of the current national threat level. It is especially important given the current national threat. Sharing national threat levels with the general public keeps everyone informed. It explains the context for the various security measures (for example airport security or bag searches) which we may encounter in our daily lives.

If you have information about possible terrorist activity, call the Anti-Terrorist Hotline: 0800 789 321.

The Anti-Terrorist Hotline is for tip-offs and confidential information. For warnings about possible bombs or other urgent threats please call 999.

Threat level history

Since 2006, information about the national threat level has been available on the MI5 and Home Office websites. In September 2010 the threat levels for Northern Ireland-related terrorism were also made available.

In July 2019 changes were made to the terrorism threat level system, to reflect the threat posed by all forms of terrorism, irrespective of ideology. There is now a single national threat level describing the threat to the UK, which includes Islamist, Northern Ireland, left-wing and right-wing terrorism.