Specialist Garda units have carried out a simulated anti-terror operation in central Dublin.
The exercise involved attackers targeting people at the Docklands railway station before taking hostages on a train.
The operation was partly designed to measure response times for elite Garda units and involved officers reacting to victims of knife attacks and confronting armed terrorists.
Justice Minister Charlie Flanagan said he hoped the exercise would give the public reassurance.
"While a terrorist attack here may be unlikely, the authorities are in no way complacent in the measures being taken to respond to that threat," he said.
"The exercise today is part of an ongoing process of planning and training that, to a large extent, takes place quietly and behind the scenes. That said, this work goes on relentlessly."
The exercise began with a simulated report of a car crash at Spencer Dock to which local units were dispatched.
The scene they were confronted with included an injured person on the ground and people having been stabbed.
The officers were also told of a report of two attackers - one armed with a gun and one a knife.
The exercise then moved inside the station.
The exercise was brought to an end by armed gardai who detained one of the supposed knife-wielding attackers in the train station and the gunman after he stepped off the train.
The rapid response was played out on cordoned-off streets and with the station temporarily closed.
The current terror threat level in Ireland is described as moderate.
Taoiseach Leo Varadkar marked the operation by announcing that t he first meeting of the new Government Security Committee will take place next week.
"Protecting our citizens is of paramount importance to the Government. This involves a significant amount of ongoing work by the gardai, the Defence Forces and other state agencies," Mr Varadkar said.
The Taoiseach said the exercise was about developing and assessing the capacity to prevent or respond to incidents.
"Their principle focus is on security within Ireland, but they also work with our partners in Europe and further afield. Much of this work happens behind the scenes, but I also recognise that the public need reassurances about our capacity to deal with incidents," he said.
Mr Varadkar emphasised the need to focus on prevention.
"We do this through our law enforcement and intelligence agencies, through international co-operation, through our foreign policy and peacekeeping work, and also through important domestic measures such as promoting integration, education, tolerance and respect here at home," he said.
The Government Security Committee is designed to ensure more cooperation between ministers and across departments to prepare for and manage security threats.