IRA renegades have honed their "engineering" skills in creating homemade anti-tank type weapons that can penetrate armour.
ardaí have uncovered evidence confirming that dissident republicans have made significant progress in developing their terror technology.
Recent attacks by the dissident groups in Northern Ireland heightened fears among senior anti-terrorist police officers on both sides of the border that their technology advances were likely to signal a new spate of attacks on PSNI vehicles and stations.
But the scale of their technological advances was not fully known until garda finds in dissident hideouts were forensically examined.
A senior officer told the Irish Independent last night: "This is a very worrying development and there are serious concerns on both sides of the border.
"The seizures have undoubtedly delivered a major setback to their deadly plans and the operation must be regarded as one of the most important strikes against the dissidents for several years.
"But it also demonstrates that, despite seizures and arrests in the past, they are continuing to develop their bombing capacity and manufacture homemade weapons", he added.
The evidence shows that the "engineering" section of one breakaway group, known as ONH, has been focusing on a new rocket-propelled anti-tank weapon, which can cause more death and destruction than their previous campaign of mortar attacks.
Since 2013, there has been evidence that the various groups have been improving the capacity of their mortars but the vast majority of their attacks have either been foiled or unsuccessful.
It is estimated by security officials in the North that for every attack carried out by the dissidents, almost another four were thwarted.
Many of the homemade missiles were manufactured in the border region, south and north, but gardai have also uncovered bomb factories deeper into the Republic where the terror technicians were concentrating on boosting their electronic capabilities.
Recent evidence indicates that they have been working on improving remote detonation of improvised explosive devices.
And it is understood that some of the electronic component equipment, discovered in the recent searches, was not known previously to have been in the possession of the dissidents.
The IRA's most devastating mortar attack took place at Newry RUC station in 1985 when nine police officers were killed and 37 people were injured.