The UK Threat Levels are the alert states that have been in use since 1 August 2006 by the British government to warn of forms of terrorist activity. Before then a colour-based alert scheme known as BIKINI state was used.[1] The response indicates how government departments and agencies and their staffs should react to each threat level.
Since 24 September 2010, the Home Office has reported three different categories of terrorist threat:[3][4]
Threat from international terrorism.
Terrorism threat related to Northern Ireland in Northern Ireland itself.
Terrorism threat related to Northern Ireland in Great Britain.
The Joint Terrorism Analysis Centre (JTAC) is responsible for setting the threat level from international terrorism and the Security Service (MI5) is responsible for setting both threat levels related to Northern Ireland.[5]
Maximum protective security measures to meet specific threats and to minimise vulnerability and risk. Critical may also be used if a nuclear attack is expected.
Severe
An attack is highly likely.
HEIGHTENED
Additional and sustainable protective security measures reflecting the broad nature of the threat combined with specific business and geographical vulnerabilities and judgements on acceptable risk.
Substantial
An attack is a strong possibility.
Moderate
An attack is possible, but not likely.
NORMAL
Routine protective security measures appropriate to the business concerned.