The reasons behind terrorist attacks in Great Britain are many. During the 20th century, most attacks were carried out by various Irish Republican Army (IRA) groups and were linked to the Northern Ireland conflict (the Troubles). In the late 20th century there were also isolated attacks by Middle Eastern terrorist groups, though it was still the fact that the vast majority of the attacks were the work of the IRA and allied groups. During the 21st century, however, most terrorist incidents in Britain have been linked to Islamic fundamentalism.