Terrorism in the United Kingdom

Terrorism in the United Kingdom, according to the Home Office, poses a significant threat to the state.^[1] There have been various causes of terrorism in the UK. Before the 2000s, most attacks were linked to the Northern Ireland conflict (the Troubles). In the late 20th century there were also attacks by Islamic terrorist groups. Since 1970, there have been at least 3,395 terrorist-related deaths in the UK, the highest in western Europe.^[2] The vast majority of the deaths were linked to the Northern Ireland conflict and happened in Northern Ireland.^[2] In mainland Great Britain, there were 430 terrorist-related deaths between 1971 and 2001. Of these, 125 deaths were linked to the Northern Ireland conflict,^[3] and 305 deaths were linked to other causes,^[4] including 270 in the Lockerbie bombing.^[4] Since 2001, there have been almost 100 terrorist-related deaths in Great Britain.

The UK’s CONTEST strategy aims to prevent terrorism and other forms of extremism.^[5] It places a responsibility on education and health bodies to report individuals who are deemed to be at risk of radicalisation.^[5]: 35 The 2023 CONTEST report indicated that 75 per cent of the Security Service (MI5)'s caseload was from monitoring Islamist threats.^[6] In 2023, 80% of the Counter Terrorism Police network’s live investigations were Islamist while 10% were Extreme Right-Wing.^[7] In 2024, polling by YouGov found that half of the public in Great Britain believed that Islamic extremists were the biggest extremist threat. 76% considered Islamic extremists to be a “big” or “moderate" threat, although attitudes differed significantly along political lines.^[8]

1,834 people were arrested in the UK from September 2001 to December 2009 in connection with terrorism, of which 422 were charged with terrorism-related offences and 237 were convicted.^[9]