The new commissioner of An Garda Síochána has said dissident republican terrorism remains "the biggest threat on the island of Ireland".
Drew Harris said it is important to protect Ireland "and our neighbouring nations against terrorist attack".
He was speaking at his first press conference since taking up the role.
He spent much of the time answering questions about his previous role as a former Police Service of Northern Ireland (PSNI) officer.
Mr Harris has a policing career spanning 35 years, starting in the Royal Ulster Constabulary (RUC).
For the past four years he had been second in command of the PSNI, serving as deputy to Chief Constable George Hamilton.
"We have to work very closely with our European partners, the other police services, Europol and the other security services to help secure this nation and our neighbouring nations against terrorist attack," said Mr Harris.
"We form part of a network and it's important that we share information and follow through investigations with each other.
"The international terrorists are very effective at working internationally, we too must be as well if we're to combat that threat.
"There has been a lot of success against them and some of that threat has been eroded and diminished, but we are very aware that these people are full of intent and determination to carry out attacks."
He also said he would be working with the PSNI to secure the border and prevent an increase in organised crime and terror-related activities.
'I am Irish'
Mr Harris said he was in the role "as a public servant to do a good job in terms of protecting the people".
"I am Irish and I'm not sure how much of an outsider I am really," he said.
"I'm a police officer, I've joined a police organisation, I'm from the island of Ireland, I've always worked for the benefit of the people of Ireland.
"I've worked closely with An Garda Síochána in that respect as well.
"I'm here to lead the organisation and I trust that the organisation will assess me on its merits as well.
"There's a lot of comment in respect of change, but all of these things are there so that we can better provide a service."