The two Real IRA factions in Dublin and Derry are believed to possess the greatest capability to launch an attack on Britain, the Irish Post reports.
Despite this the British Intelligence agency MI5 advised the British Government to downgrade the threat level from Northern Ireland-related terrorism from substantial to moderate last October.
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A statement from the Home Secretary Theresa May said that a "terrorist attack is possible, but not likely" to be carried out in England, Scotland or Wales by Irish Republican Army dissidents.
Commenting on the growth of the Real IRA, a senior source told the Post that many factions of the dissident group are using the organization as a front for criminality.
“There are little units here and there, but they are small in number and it would appear they have failed to import any sizeable munitions from anywhere,” a senior security source told The Irish Post.
“Through decommissioning it has been established that 90 per cent of weapons and bomb making materials were handed over, that’s about as good as you are going to get because there are people who have been killed that previously stashed weapons.
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“The whole structure of the old Provisional IRA is gone, the Chief of Staff — that went with giving up the arms, and the whole general grouping there. It’s well established there is no Real IRA army council.
“It’s largely fundraising gangsters in Dublin and they call themselves dissident. It’s smuggling, diesel laundering and laundering the money they achieve in this. They’ve gone away from major robberies. You don’t hear of Dublin gangsters being stopped when they come out of Belfast, the factions are answerable to no one really, they are quite splintery in structure and localised.”