Dissident Irish republicanism
Since 1997, when the Provisional Irish Republican Army called an end to its armed campaign in Northern Ireland and England, dissident Irish republican paramilitary groups have sought, via a campaign of economic sabotage and physical force violence against agents of the British and southern Irish governments, to force Northern Ireland to secede from the United Kingdom and join a unified Ireland.
To date, two soldiers and three policemen (two members of the PSNI, and one of its predecessor, the RUC) have been murdered as part of the campaign, whilst one PSNI officer has been seriously injured by a car bomb.
Background
Since the 1169 invasion of Ireland by Anglo-Norman knights at the request of the ousted King of Leinster, Dermot MacMurrough, Ireland has, in part or in whole, been under English, and later British, administration. Rebellions against rule from Great Britain were unsuccessful until 1919–1921's Anglo-Irish War, when the original Irish Republican Army#Origins (IRA) succeeded in removing 26 of Ireland's 32 traditional counties from the United Kingdom of Great Britain and Ireland as the Irish Free State. The remaining six counties, located in the province of Ulster, however, became Northern Ireland and remained a part of the newly-Christened United Kingdom of Great Britain and Northern Ireland.
A civil war followed in the new southern state, and the IRA split for the first time, into the Irish National Army – the war's victor, which became the army of the Free State – and the Anti-Treaty IRA, which was opposed to the treaty that had partitioned Ireland between two states.
The IRA ceased to be a significant force following its defeat in the Civil War, and it wasn't until a further split, into the Official IRA and Provisional IRA (PIRA) following the 1969 Northern Irish riots, that a group calling itself the Irish Republican Army – this time the Provisionals – again proved a significant paramilitary force. As a belligerent in what would come to be known as The Troubles, the PIRA waged an armed campaign against Britain that lasted until 1997 and claimed around 1800 lives.
The PIRA called an indefinite ceasefire in 1997 and de-commissioned its arms in 2005, but a number of hardline splinter groups, known as dissident republicans, have vowed to continue using "armed struggle" to achieve the republican aim of a united Ireland.