Gli uomini compariranno davanti alla Special Criminal Court.
Due di loro sono stati arrestati sulla M1 vicino a Dundalk nella serata di martedì.
Gli altri due sono stati arrestati nella successiva operazione eseguita a Dundalk e Dromiskin.
Tutti sono stati tenuti in custodia in base alla Offences Against the State Act (Legge per i Reati Contro lo Stato).
Tratto da Rté
Four in court over mortar seizure in Louth
The men will appear before the Special Criminal Court later this morning.
Two of the men were arrested after gardaí stopped a car on the M1 near Dundalk on Tuesday night.
The two others were arrested during follow-up operations in Dundalk and Dromiskin.
All have been held in custody since under the Offences Against the State Act.