REUTERS - A bomb in a hijacked taxi exploded on Monday behind a British army barracks in County Down, a police spokeswoman said.
Here are details of some of the major dissident incidents in Northern Ireland in the last year.
March 7, 2009 - Gunmen kill two British soldiers and wound four at the Massereene base near Antrim. The Real IRA later claims responsibility.
-- Two days later the Continuity IRA, another splinter group formed out of the Provisional IRA and that also seeks the removal of British influence from the province, says it shot dead a police officer in Craigavon, 25 miles (40 km) southwest of the Northern Ireland capital Belfast.
Sept. 8 - Police say army experts make safe a bomb containing 600 lb (272 kg) of explosives, bigger than the device which killed 29 people in Omagh in 1998. The bomb is discovered in Forkhill in Armagh, on the border with the Irish Republic.
Sept. 11 - The Real IRA claims responsibility for planting a small bomb outside the house of a police officer’s parents.
Oct. 16 - A car bomb injures a Northern Irish police officer’s partner.
Oct. 22 - A bomb explodes at a British Territorial Army base, causing no injuries. Police say they believe the device was thrown over the front gate of the compound.
Nov. 19 - Army experts defuse a bomb aimed at police officers.
Nov. 21/22 - Gunmen ambush and shoot at police in the village of Garrison, 25 miles (40 km) from Enniskillen. No one is hurt. Two people are arrested in connection with the ambush.
-- A car with a 400 lb (180 kg) bomb is driven through the security barrier at the Belfast headquarters of the Northern Ireland Policing Board and and partly explodes. No one is hurt.
Jan. 8, 2010 - Republican militants seriously injure a police officer when they explode a bomb under his car in County Antrim, northwest of Belfast.
Feb. 22 - The Real IRA is blamed for a car bomb attack outside a courthouse in Newry, as well as gun and pipe bomb attacks on police stations in Belfast and on towns near the border with the Republic of Ireland.
-- The Newry bomb contained what police estimated to be 250 pounds (115 kg) of explosives and caused extensive damage, although no-one was hurt.
March 20, 2010 - Police come under gun attack south of Newry, while investigating a security alert that led to the closure of the Belfast-to-Dublin railway line.
April 12 - Minutes after the transfer of police and justice powers to Belfast from London is completed, a bomb in a hijacked taxi explodes, injuring one man. The explosion was at the barracks housing the hq of spy agency MI5 in the province. The Real IRA claimed responsibility for the blast.