Explosives, firearms and ammunition discovered in Dublin last week included Provisional IRA weapons that should have been decommissioned, according to the gardaí.
15kg of semtex explosive along with handguns, shotguns, a sub-machine gun, electronic devices and over 1,300 rounds of ammunition were found on land at the Old Airport Road in Cloghran.
It is the largest ever dissident republican arms and explosives find.
The seizure is also significant as it appears to indicate that not all of the Provisional IRA's guns and bombs have been decommissioned.
Superintendent David Taylor said the seizure is a major blow to the activities of dissident republicans.
He said the only function of the guns and bombs is to kill and maim and there is no doubt that the seizure has saved lives.
Gardaí say the semtex discovered is old and very different from what is currently available, which is more rigorously controlled and harder to acquire.
The range of electronic devices recovered also includes mobile phone blockers.
Replica and real guns including an UZI 9mm sub machine gun, revolvers, double barrel shotguns, pistols, an air rifle, a tazer and a silencer were also found.