Senior security sources do not accept the suggestion inherent in the catchphrase "trust in rust" that the IRA's weapons will fall into disrepair in the near future.
Experience has shown that the IRA carefully prepares its weapons for storage, oiling all moving parts.
Since the 1980s the organisation has also built damp-proofed bunkers to store weapons securely.
One senior source said a properly oiled AK47 assault rifle, of which the IRA may have more than 1,000, would be usable 100 years from now.
Also, the estimated three tons of the Czech-manufactured Semtex-H explosive has a "shelf life" of 35 years and would be usable long after that. The Semtex is the most destructive part of the IRA arsenal.
There has been no indication from the IRA that it intends disposing of any of its store of the plastic explosive.
The bulk of the arsenal was donated to the IRA by one of its main sponsors, the Libyan regime of Col Muammar Gadafy.
The arms in the two dumps inspected by the international weapons inspectors are almost certainly gifts from the Gadafy regime.
The weapons shipments from Libya began in 1972 with two cargoes containing an estimated 500 rifles, 500 pistols, 40,000 rounds of ammunition, an unknown amount of gelignite and TNT and assorted grenades, anti-tank mines, fuses and other equipment.
A third shipment on board the MV Claudia was intercepted off Helvick Head, Co Waterford, in March 1973.
A further seven tons of weapons, including an unknown number of RPG7 rocket-launchers, rifles, explosives, handguns and ammunition, reached the IRA from Libya between 1977 and 1978.
The bulk of the IRA's arsenal arrived in this State from Libya between August 1985 and the summer of 1987.
The weapons arrived in four shipments on two ships skippered by the former Bray Travel owner, Adrian Hopkins.
The first three shipments contained a total of between 34 and 44 tons of weapons. The fourth shipment carried 80 to 90 tons of weapons.
The first shipment included 50 boxes containing rifles, pistols and rocket-launchers. The second was similar with the addition of dozens of 12.7mm light machineguns. The next shipment in April 1986 contained between 14 and 20 tons of weapons, including Semtex and at least two surface-to-air missiles.
The largest shipment arrived in early 1987. The contents of the Villa, a ship bought by the IRA for the gun-running, included between 80 and 90 tons of weapons, together with at least seven RPG rocket-launchers, 10 SAM missiles and a large quantity of Semtex.
In October 1987 this gun-running route was discovered by accident when French customs on the look-out for drug-traffickers boarded another gun-running ship, the Eksund, in the Bay of Biscay.
The Eksund contained 150 tons of weapons including 1,000 AK47 rifles, 10 DMZK .5 antiaircraft machineguns, one million rounds of ammunition and one million mortar shells.
After the shipments arrived from Libya in 1985-87, the IRA no longer needed infantry weapons and turned to sources in the United States and Europe for electrical components for its increasingly sophisticated bomb-making factories.
Three of those factories were uncovered by gardai: at Kilcock, Co Kildare, in March 1993; at Clonaslee, Co Laois, in June 1997; and at Redhills, Co Cavan, in February 1998.
In the 1980s and 1990s the IRA bought electronic parts through agents on the east coast of the United States and acquired electric detonators and a number of the .5 Barrett sniper rifles, which were later used to kill nine soldiers and police in south Armagh.
The IRA still has a number of sniper rifles and may have acquired more after calling its ceasefires in the 1990s.
The increasing adaptation of home-made weapons during the 1980s and 1990s meant that the infantry weapons, like the assault rifles and machineguns from Libya, were used less and so went into long-term storage.
The procurement of weapons continued after the ceasefires were called.
In 1999 an IRA team bought around 200 handguns and sub-machineguns in Florida and sent them through the postal system to safe houses in the Republic.
Some of the handguns were used subsequently to assassinate a number of people the IRA accused of drug-dealing.