Terrorism in the United Kingdom , according to the Home Office , poses a significant threat to the state . 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 Middle Eastern terrorist groups , most of which were linked to the Arab – Israeli conflict . Since the 2000s , most terrorist incidents in Britain have been linked to Islamic extremism . Since 1970 , there have been at least 3,395 terrorist-related deaths in the UK , the highest in western Europe . The vast majority of the deaths were linked to the Northern Ireland conflict and happened in Northern Ireland . 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 , and 305 deaths were linked to other causes – most of the latter deaths occurred in the Lockerbie bombing . Since 2001 , there have been almost 100 terrorist-related deaths in Great Britain , the vast majority linked to Islamic extremism
Lockerbie bombing
Pan Am Flight 103
Terrorism in the United Kingdom