The planned raids, carried out by An Garda Siochana from the Special Detective Unit, were the result of an ongoing investigation into dissident republicans activity.
A total of 20 searches were carried out in Counties Louth, Dublin and Wexford earlier this morning.
The operation, targeting important dissident figures, was carried out with the assistance of the Garda Emergency Response Unit, the Technical Bureau, the Dog Unit and uniform and detective Gardai from the Louth and Wexford Divisions.
As part of this investigation four males were arrested. One was a man in his 60s and the other three in their 20s.
All are currently detained under Section 30 of the Offences Against Act at various Garda Stations in the Dublin Metropolitan Region.
They were arrested for offences such as directing terrorism, membership of an unlawful organisation and possession of explosives. Gardai also recovered a suspect device from a property Courtown, County Wexford.
The area has been cordoned off and the Army Explosive Ordnance Disposal team are on their way to the scene.
Gardai have also recovered component parts for explosives devices at some of the other locations searched. All component parts will now be subject to technical examination.
In a seperate incident but also related to dissident activity, gardai stopped a car at Glenfarne on the N16 (Sligo to Blacklion Rd) yesterday morning. On searching the vehicle they discovered a pistol and suspected component parts for explosives.
Two males in their 20’s were arrested at the scene and are currently detained under the provisions of Section 30 of the Offences Against the State Act at Manorhamilton Garda Station.