Two Dublin-based suspected senior members of the so-called New IRA have been targeted in a massive series of raids against the terror organisation.
A major cross-Border operation targeting the terror organisation began at dawn yesterday with multiple searches linked to leading dissident Republicans in Northern Ireland.
There were 10 arrests in the North, with six searches being carried out in the Republic, resulting in no arrests.
In Dublin, senior sources said one of those targeted by the The Garda Special Detective Unit (SDU) is a 53-year-old north inner city criminal who has a previous conviction for handling stolen property and has been a major target for specialist gardaí for years.
Another of those targeted in the capital is a 59-year-old Crumlin man who was previously jailed at high security Portlaoise Prison for IRA membership and also has a previous conviction for being involved in an armed robbery.
"There were no plans to arrest anyone this morning by gardaí as the SDU was acting as an ancillary to a PSNI investigation, which led to a number of arrests north of the Border," a senior source told the Herald.
"But devices and documentation that could be very crucial to this cross-Border investigation have been seized by gardaí.
"You are talking here about a number of very serious individuals who have been under detailed surveillance by both police agencies for a number of months now and yesterday's raids were part of that investigation," the source explained.
The six searches by gardaí were carried out in counties Dublin, Cork, Laois and Kerry.
The 10 arrested in the North are being held under the Terrorism Act.
"An Garda Síochána carried out a number of searches in support of an operation led by the Police Service of Northern Ireland," a Garda spokesman said.
The New IRA is considered the largest dissident republican group and has been behind numerous attempted attacks on police officers in the North.
Tragic journalist Lyra McKee was shot dead by a New IRA gunman while observing a riot in Derry in April of last year.
In the North, properties were raided in Derry, east Tyrone and Belfast as part of the PSNI probe against the dissident mobsters.
Yesterday's raids were among the most significant carried out by the gardaí's SDU since last March where they targeted a quarry where suspected pipe bombs were being made by dissident republicans.
That search operation on the Carlow/Kildare border followed the arrest of three men by heavily armed gardaí.
They were all later released without charge.
Members of the terrorist network tried to get involved in the Hutch/Kinahan feud which has claimed 18 lives but backed off after the feud related gun murder of Michael Barr (36), who was shot dead in the The Sunset House pub in Dublin's north inner city on April 25, 2016 by the Kinahan cartel.
In March of last year, their leader in the Republic - Kevin Braney (45), of Glenshane Crescent, Tallaght - was found guilty by the Special Criminal Court of the "premeditated" murder of fellow dissident republican Peter Butterly (35) as part of an internal IRA dispute.
Butterly was gunned down outside The Huntsman Inn in Co Meath on March 6, 2013.
Braney is currently locked up in high security Portlaoise Prison.