The Special Detective Unit carried out the raid.
Three men in their forties and fifties have been arrested in the midlands in a search targetting dissident Republican groups.
The Special Detective Unit, backed up by armed officers and garda dogs carried out the raid.
All three men have been detained under Section 30 of the Offences Against the State Act, which means they can be held for up to 3 days.
They've being held in Dublin as searches continue -- with Gardaí saying this remains a "live operation".