Threat levels are designed to give a broad indication of the likelihood of a terrorist attack. There are 5 levels of threat: low: an attack is unlikely moderate: an attack is possible but not likely substantial: an attack is a strong possibility severe: an attack is highly likely critical: an attack is expected imminently. The level is set by the Joint Terrorism Analysis Centre and the Security Service (MI5). Threat levels don’t have an expiry date; they can change at any time as different information becomes available to security agents. The current threat from terrorism can be viewed on the MI5 website. Threat levels in themselves do not require specific responses from the public. 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. The police and the security and intelligence agencies depend on information from the public. You should always remain alert to the danger of terrorism and can help to keep yourself, your family and your local community safe by reporting any suspicious activity.