Gardaí have discovered explosives, guns and ammunition during searches on a site at Omeath in Co Louth.
The operation was a follow-up to an investigation targeting dissident republican activities.
Further searches were carried out near Omeath on Thursday.
This operation involved Gardaí from the Louth Garda Division, Special Detective Unit and from Special Tactics & Operations Command.
In a statement, Gardaí said they recovered a quantity of explosives, two firearms and a “sizeable” quantity of ammunition of various calibres.
An Explosive Ordinance Disposal unit of the Irish Defence Forces later visited the site and some of the material was destroyed by a controlled explosion.
Investigations are ongoing – but Gardaí have said there will be no further comment “for operational reasons.”