A Russian-made rocket launcher - a weapon once used by the IRA before the Provisionals declared an end to their armed campaign - has been found at an unoccupied house in west Belfast.
Security chiefs believe the RPG-7 device and a warhead were being stored by dissident republicans in preparation for an attack on a police patrol in the city.
But they are also alarmed the anti-tank rocket-propelled grenade, which can penetrate armour plating, turned up years after the Provisionals were supposed to have decommissioned all their weapons as part of the Good Friday peace agreement.
Details of the type and amount of weaponry the IRA reportedly put beyond use under the supervision of General John de Chastelain, the head of the international decommissioning body, have never been revealed.
Ex-IRA men who quit the Provisionals because of their opposition to the Sinn Fein peace strategy are known to have kept some weapons and explosives.
But this is believed to be the first time an RPG-7 has been recovered in Northern Ireland since all the guns and ammunitions were reportedly decommissioned.
Police said lives were undoubtedly saved with the finding of the launcher and warhead in a house at Hawthorn Street, off the Springfield Road.
A PSNI spokesman said: "This is a significant seizure in that it shows the continuing intent of dissident terrorists to inflict death and serious injury. It also displays the callous disregard these small groups have for the lives of those in local communities, given where it was stored and its potential in injure or kill anyone in the vicinity of where it would have been fired.
"The seizure is still under active investigation and police inquiries are continuing. We would ask everyone in the community to work with us to remove these weapons from our streets. Police will continue to use every lawful means to disrupt and dismantle groups committed to violence.
"We would appeal for anyone with information about any such activity to contact us so that we can protect life and property and bring offenders before the courts."