The IRA has amassed formidable stocks of weapons over the years, some of them smuggled from America and the Continent but most of themprovided in the mid-1980s by Colonel Muammar Gaddafi's Libyan regime.
Several shiploads of guns smuggled from Tripoli to Ireland gave the IRA an arsenal that is normally the preserve of a small country. Some of this has been recovered over the years by the security forces but much of it remains undetected.
Security sources have incomplete knowledge of exactly what is out there, describing their picture of the IRA armoury as a guesstimate.
They believe the IRA has in the region of 1,700 weapons, of which more than a thousand are rifles and between 500 and 600 are handguns. It also has about 50 heavy and general purpose machine-guns.
The organisation acquired large amounts of Semtex plastic explosives from Libya, which it has used in home-made weaponry including grenades, mortar shells, rockets and under-car boobytraps.
It is thought to have more than two tons of this left. Although some of the Semtex has been in the IRA's possession for more than 15 years, the chemical does not appear to lose its explosive power and become unstable with the passage of time, as happened with old-fashioned gelignite.
The IRA is also believed to hold a variety of heavy weaponry, which includes RPG-7 rockets, sub-machine-guns, grenades and a number of ground-to-air missiles.
On the loyalist side, although the extreme Protestant groups are much bigger than the IRA they have fewer guns and none of the heavy weaponry. Their stock, which is distributed among a number of groups, is thought to add up to between 900 and 1,000 weapons, almost 600 of which are handguns.