The attack on prison officer Adrian Ismay is the latest in a spate of violent dissident activity.
:: March 2009 - Two soldiers, Sappers Patrick Azimkar and Mark Quinsey are shot dead by the Real IRA outside Massereene military barracks in Co Antrim. Just 48 hours later, police officer Stephen Carroll is shot dead while responding to a call in Craigavon, Co Armagh.
:: January 2010 - Catholic police constable Peadar Heffron, 33, is seriously injured when a booby trap device detonates under his car about a mile from his home in Randalstown, Co Antrim.
:: January 2010 - The Real IRA fire shots at a police station in Bessbrook, Co Armagh. No one was injured.
:: February 2010 - Kieran Doherty, 31, is found shot dead close to the border in Co Londonderry. The Real IRA said it was responsible for the murder of Mr Doherty, who was one of its members.
:: February 2010 - A bomb explodes outside Newry courthouse. There are no reports of any injuries but damage is caused to the gates of the court.
:: April 2010 - A bomb explodes outside Newtownhamilton police station causing considerable damage.
:: April 2010 - A bomb in a hijacked taxi explodes outside Palace Barracks in Holywood, which includes the MI5 headquarters, injuring one man.
:: August 2010 - Three children suffer minor injuries when a bomb explodes in a bin in Lurgan, Co Armagh.
:: April 2011 - Catholic police recruit Ronan Kerr, 25, is killed when a bomb explodes under his car at his home in Omagh, County Tyrone.
:: September 2011 - The Real IRA is blamed for two bomb attacks at the home of a Catholic police officer and a retired doctor who works for the police near Claudy, Co Londonderry.
:: October 2011 - A bomb explodes outside the UK City of Culture offices in Londonderry.
:: January 2012 - A Scottish soldier finds a bomb inside his car which was parked at his girlfriend’s house in the Ligoniel area of north Belfast.
:: November 2012 - Prison officer David Black, 52, is gunned down as he drives to work at Maghaberry high security jail along the M1 motorway. The New IRA claim responsibility for his murder.
:: December 2012 - An off-duty police officer discovers a bomb under his car in east Belfast.
:: March 2013 - Police escape injury when a device explodes in a bin during a parade in Lurgan.
:: October 2013 - Dissident republicans are blamed for a series of letter bomb attacks. Packages addressed to Secretary of State Theresa Villiers and two senior police officers are made safe.
:: November 2013 - A car bomb in a hijacked vehicle partially explodes close to the Victoria Square shopping complex in Belfast city centre. No one is injured.
:: December 2013 - A bomb in a sports bag explodes in Belfast’s Cathedral Quarter disrupting Christmas celebrations.
:: February 2014 - Letter bombs are sent to army careers offices in Oxford, Slough, Kent, Brighton, Hampshire and Berkshire. Dissident republicans are blamed.
:: March 2014 - Police are attacked with a mortar in west Belfast. There were no reports of injuries and minimal damage was caused.
:: May 2014 - The reception area of a hotel in Londonderry is damaged by a fire bomb.
:: April 2015 - A bomb explodes outside a Probation Service office in Londonderry. No one is hurt.
:: June 2015 - A bomb is discovered under a police officer’s car in Eglinton, Co Londonderry. The target’s wife also serves with the PSNI, it is disclosed.
:: October 2015 - A police recruitment event in Londonderry is cancelled after a bomb is discovered in the grounds of the venue where it is due to be held.
:: November 2015 - Police officers escape injury after eight high velocity shots are fired at their patrol car in west Belfast.
:: March 2016 - Prison officer Adrian Ismay dies after a bomb explodes under his van at Hillsborough Drive in east Belfast.