Who decides threat levels?

The Joint Terrorism Analysis Centre (JTAC) was created in 2003 as the UK's centre for the analysis and assessment of international terrorism. JTAC is responsible for setting international terrorism threat levels and Ministers are informed of its decision.

It also issues warnings of threats and other terrorist-related subjects for customers from a wide range of government departments and agencies, as well as producing more in-depth reports on trends, terrorist networks and capabilities.

The Security Service is responsible for assessing the level and nature of the threat arising from domestic terrorism, principally the Irish-related terrorist threat.