There has been an upsurge in Continuity IRA activity across the north in recent months.
The organisation emerged from a split within the Provisional republican movement dating to 1986 after Sinn Féin members voted to take of take their seats in Dáil Éireann.
In 2009 it claimed responsibility for killing PSNI constable Stephen Carroll (48) in a sniper attack in Craigavon as he and colleagues attended an emergency call.
He was the first PSNI officer killed by republicans.
Read More: Continuity IRA admits responsibility for 'Brexit Day' bomb
In 2018 the organisation said it had no intention of giving up its armed campaign after Óglaigh na hÉireann called a ceasefire.
“The IRA will continue to recruit, target and train,” it warned at the time.
The group is believed to have pockets of support in several areas including north Armagh, Fermanagh and Belfast.
There have been a number of attack prior to the ‘Brexit day’ bomb underneath a lorry trailer.
In December the organisation claimed responsibility for a grenade attack on a PSNI Land Rover in west Belfast, which resulted in no injuries.
It was also behind an attempt to kill police officers in Wattle Bridge, Co Fermanagh, in August.
It is understood that on that occasion a hoax device including a command wire had been set up on hay bales in a bid to draw police into the area.
It was later claimed that a command wire was spotted and when PSNI officers arrived at the scene another bomb detonated within the police cordon.
No-one was injured in that attack.
A month earlier a fake mortar tube was used during an attempted attack in Craigavon, Co Armagh.
The tube was set up to look like a horizontal mortar and “propellant” was used to create the sound of an explosion, with the intention of drawing police into the area.
It later emerged that a bomb had been placed inside a concrete slab on which the tube was resting and would have detonated once moved.
It was detected before it exploded.
In April the group said it abandoned a bomb and command wire in a bin in Lurgan.
Police later declared the object a hoax.
In a statement to the Irish News last year the group said it attempted to kill police officers outside Dunmurry on the outskirts of west Belfast in December 2018.
According to the group a horizontal style weapon was set up to fire a single .50 calibre round at a passing police car but it failed to go off.
Pictures emerged last year of a of a masked Continuity IRA member firing shots in in a graveyard in Carrickmore on Easter Saturday.
