A member of the Green Party and a candidate in this year's General Election, Mr Ray Harrigan, was arrested this morning at Shannon Airport in connection with anti-war graffiti on a US transport aircraft.
Mr Harrigan (26) from Limerick, has since been released and a file is being sent to the Director of Public Prosecutions.
Another man - a 22 year old student - from County Wexford will appear at a special sitting of Gort District Court later this evening.
Both men were arrested at Shannon airport shortly after 5 a.m. this morning. It is believed one of them remained outside the perimeter of the airport, while the other man entered the grounds to paint anti-war slogans on the aircraft - a US Hercules transport airliner - which was parked in the same area as commercial airliners at the time.
Aer Rianta said it was carrying out a separate investigation to the gardaí and would be examining security arrangements at the airport in order to ensure an incident such as this did not happen again.
Head of operations for Aer Rianta, Mr John Reddy commented that it is being "treated very seriously".
"Hopefully the investigation will shed more light on that actually happened," he added.
Both men are understood to have been previously involved in protests against US military aircraft using Shannon as a refueling depot.
Meanwhile, the leader of the Green Party, Mr Trevor Sargent has called on the Government to release both peace activists.
"The Greens believe that the peace activists were morally right to highlight the treachery of the Irish Government in this matter as they did," he said.
Mr Sargent said that he was taking the opportunity of the Nice debates to highlight the "feigned interest by this Government for Irish neutrality".
"The use of Irish airports by the US military will not be affected in any way if the Government's meaningless declarations are supported in the forthcoming repeat referendum," he added.