Gardaí believe most of the Irish jihadis who left to fight wars are now dead or missing.
It is estimated that around 30 terror sympathisers from here went to fight wars in Iraq or Syria.
The garda in charge of Ireland's national security says they are now either deceased, missing or fighting elsewhere.
Assistant Commissioner Michael O’Sullivan says they are monitoring a small number of Isis sympathisers here.
He said: "We have a small number and I just want to elaborate on what the small number of Isis sympathisers here who we are monitoring and who are of interest to us.
"In 2017 we set up a terrorist financing investigation unit to look at terrorist financing and that includes not just the domestic, but also the international."
Mr O'Sullivan said there are around 2,000 foreign fighters left in the theatre of war, which was getting smaller.
He also said Gardaí are working with the Defence Forces and overseas agencies in setting up systems to prevent terror attacks here.
He said: "There is concern internationally in relation to where they may go next.
"We have a small number that we believe are still alive in Syria and Iraq. They may go to other theatres of war in the Philippines, in the horn of Africa, North Africa.
"Also of concern to us certainly would be families returning and that is a concern for a lot of jurisdictions and these may have been families not involved directly in the war but whose children, particularly young males may have witnessed some of the most appalling crimes known to man", the assistant commissioner added.
"They will return and they will become a challenge for a multi-agency effort".