Dissident republicans are suspected of shooting an off-duty police officer, Detective Chief Inspector John Caldwell, as he coached young people at a sports complex in Omagh.

The incident is the latest in a line of sporadic attacks on the security forces over the last 15 years committed by violent extremists opposed to Northern Ireland’s peace process.

– May 2008 – A Catholic Police Service of Northern Ireland (PSNI) officer sustains serious leg injuries when a bomb detonates under his car near Castlederg, Co Tyrone.

– 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 fires shots at a police station in Bessbrook, Co Armagh. No one is 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. No one is injured but the gates of the court are damaged.

– 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, Co 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 Derry.

– October 2011 – A bomb explodes outside the UK City of Culture offices in Derry.

– January 2012 – A Scottish soldier finds a bomb inside his car 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 along the M1 motorway to work at Maghaberry high security jail. The New IRA claims 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 bomb in a hijacked car 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 are 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 Derry. No one is hurt.

– June 2015 – A bomb is discovered under a police officer’s car in Eglinton, Co Derry. The target’s wife also served with the PSNI.

– October 2015 – A police recruitment event in Londonderry is cancelled after a bomb is discovered in the grounds of the venue.

– 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 two weeks after a bomb explodes under his van at Hillsborough Drive in east Belfast.

– January 2017 – A police officer is injured in a shooting at a filling station on the Crumlin Road in Belfast. The garage’s busy forecourt is sprayed with automatic gunfire in the attack.

– February 2017 – A device explodes close to a police officer’s car in the Culmore area of Derry.

– January 2019 – A bomb placed in a van explodes outside the courthouse in Derry. Police blame the blast on the New IRA.

– March 2019 – The New IRA claims responsibility for sending small explosive devices in the post to two airports and a train station in London and the University of Glasgow.

– April 2019 – Journalist and author Lyra McKee, 29, is shot dead by dissidents while observing rioting in the Creggan area of Derry. The New IRA claims the attack. Several men are currently awaiting trial charged with the murder.

– June 2019 – An unexploded bomb is found under a police officer’s car parked at Shandon Park Golf Club in Belfast. The New IRA claims responsibility for the failed murder bid.

– July 2019 – A device explodes in Craigavon. Police blame dissident republicans and say it was a clear attempt to murder police officers.

– August 2019 – A bomb detonates near the border in Co Fermanagh. The attack at Wattlebridge is blamed on the Continuity IRA. It is seen as another bid to target police and Army bomb disposal officers.

– September 2019 – A bomb in an “advanced state of readiness” is found in the Creggan area of Derry. Police said the device, attributed to the New IRA, was designed to kill police officers.

– August 2020 – The alleged leadership of the New IRA suffers a major blow with a series of arrests prompted by an MI5 surveillance operation.

– April 2021 – A bomb is placed beside a car parked outside the home of a female officer in Dungiven, Co Derry.

– March 2022 – The Government lowers the threat level for dissident republican attacks in Northern Ireland from severe to substantial. The threat had severe – the highest level – since 2010.

– November 2022 – A police patrol vehicle sustains damage after being targeted by an explosive device in Strabane, Co Tyrone. Days later a viable explosive device is discovered in a hijacked car left outside Waterside PSNI station in Derry.