Elite military units have conducted a counter terrorism exercise involving a staged hijacking of a ferry heading for Dublin Port.
The Defence Forces special forces unit, the Army Ranger Wing, led the operation, assisted by the Air Corps and the Naval Service.
The live exercise involved the ARW boarding the Stena Line ferry by sea and by air and re-taking control of the vessel.
Last October, the British naval special forces unit boarded a hijacked tanker off the Isle of Wight and arrested seven people.
In a statement, the Defence Forces said that on Thursday morning “Óglaigh na hÉireann conducted a complex exercise in the vicinity of Dublin Port”.
It said: “The joint operations maritime counter terrorism exercise was led by the Defence Forces Special Operations Task Group, the Army Ranger Wing, and supported by the Air Corps and Naval Service with a Defence Forces HQ Command and Control (C2) element."
It said the scenario exercised the command and control, communications, intelligence and surveillance gathering capabilities of the Defence Forces.
The statement said: “The Army Ranger Wing successfully deployed assault team elements by sea and by air onto a Stena Ferry before securing the vessel as it approached Dublin Port.
“LÉ James Joyce and the Air Corp’s CASA were used to locate, track and provide surveillance of the ferry.”
It said the ARW assault teams simultaneously boarded the ferry from AW139 Helicopters and Rigid Hull Inflatable Boats before securing the vessel.
The statement said: “The robust and highly pressurised nature of the exercise saw personnel face a realistic training environment which required an extremely high level of expertise, execution and skill.” The Defence Forces thanked Stena Line for its assistance.
Dr Edward Burke, Director of the Centre for Conflict, Security and Terrorism at University of Nottingham, welcomed the operation, though noted the demands on the ARW.
“This is a very valuable exercise to counter a real threat to Ireland’s maritime security,” he said. “Unlike other similarly sized European countries, Ireland lacks a separate, dedicated naval Special Forces unit or capability.
"It is testament to the versatility (and pressures on) the relatively small ARW that they are also committed to providing this national security capacity.”
Security writer Don Lavery said: “The SOF [Special Operations Forces] unit would be the first to be called upon if a hijack incident or an attack on a ship or offshore rig took place.
“It needs good planning, training, skillsets and close co-operation - and a little luck - to carry it off successfully.”
He said the British Special Boat Service used similar tactics retaking an oil tanker hijacked by stowaways last October.
"This operation was very useful for Ireland given the level of maritime traffic off the Irish coast," he said.
“The exercise also shows how the ARW can operate successfully in the maritime sphere with limited resources,” he added.
He said the unit was still not equipped with its own dedicated helicopters.