Two American anti-war protesters in their 80s have been convicted of interfering with the operation of Shannon Airport, but acquitted on charges of trespass and criminal damage.

The two men, described by an airport officer as the "nicest, most courteous protesters" ever encountered, had pleaded not guilty to charges of criminal damage, trespass and interfering with the operation of Shannon Airport just over three years ago.

85-year-old Ken Mayers and 80-year-old Tarak Kauff, who have addresses in the United States, walked on to a taxiway at the airport on St Patrick's Day in 2019, wearing high-vis vests bearing the words 'Veterans for Peace'.

They said they intended to inspect a plane used to transport US military personnel and were protesting against the use of Shannon by the US as a stopover en route to areas such as the Middle East.

The runway had to close for a period of time and a plane which was due to land could not do so while the runway was closed.

The jury began deliberating on Friday and had been considering the verdicts for almost six hours in total.

The guilty verdicts were majority 10:2 verdicts. They face a maximum penalty of two years in prison or a fine.

The men were remanded on bail and will be sentenced tomorrow.

The trial heard Ken Mayers from Santa Fe in New Mexico and Tarak Kauff of Woodstock in New York both served in the United States military before becoming anti-war activists in the 1960s.

The prosecution said that on the morning of 17 March 2019, the men cut through the perimeter fence at Shannon Airport. Gloves and bolt cutters were later found inside the grounds.

Airport personnel saw two men in high-vis jackets on a taxiway in the airport, one of them carrying an Irish flag.

The men admitted being involved in making an opening in the fence and entering the airport lands but they each pleaded not guilty to criminal damage, trespass and interfering with the operation, safety or management of an airport. The damage to the fence was valued at €590.

When they were stopped by a fire officer, the men told him they were peace protesters and were going to check an American aircraft. Richard Moloney said they were the "nicest and most courteous protesters" he had ever met in his 19 years at Shannon Airport.

He said they were wearing high-vis vests with the words 'Veterans for Peace' and one of them was holding a document with a picture of an Omni Air aircraft on it.

The court was told this was a civilian airline which also transports American military personnel and on the day in question, an aircraft that had transported US military was awaiting maintenance on the airfield.

The court heard the men intended to inspect the plane and were holding a folded banner saying 'US veterans say respect Irish neutrality. American war machine out of Shannon Airport'.

The airport was shut down for 30-40 minutes after the pair were discovered.

The men were arrested and spent 13 days in Limerick Prison after initially being refused bail.

The member in charge at Shannon Garda Station said the two men were the "best custodians he had in 25 years".

In their evidence at Dublin Circuit Criminal Court, the men said their actions were legal under international law.

Mr Kauff told prosecuting counsel, Tony McGillicuddy, that he was acting on his own moral beliefs when he damaged the fence.

He said the US and Irish governments had been breaking the law and Irish people were sick and tired of their Government cow-towing to the US. He claimed there was a higher purpose than the law which says you can’t trespass or cut a fence.

Mr Kauff said he had friends who had taken their own lives because of what they had done while in the US military. He told Mr McGillicuddy, that was the real damage and damaging a fence was nothing.

"Nobody died," he said and told Mr McGillicuddy, he expected he should understand that as well.

Both men alleged the Irish Government was in breach of international law and Ireland’s neutrality by allowing planes contracted to the US military to transition through Shannon Airport.

Mr Mayers said if a belligerent country landed in a neutral country, that country had an obligation under international law to inspect the plane. He said the use of Shannon by the US military was part of the process of killing many, many people and he said what the US government was doing was a great disservice to the Irish people.

He said he and Mr Kauff understood the Irish people were very conscious of the importance of Irish neutrality.

Mr Mayers said he knew he was making an intervention that would violate a statute. But he said this was to "prevent something worse". And he said he took his action to save lives.

He said they hoped that by entering the airfield they would persuade and encourage airport police and gardaí to inspect the plane. He said at times it was necessary to go beyond the laws of a State to get a point across.

He said he took action in defence of people who were seriously being attacked. And he said he decided to break the law in order to serve a higher purpose. The authority for his actions, he said, was the obligation to do what is right.

Mr Mayers said he was a habitual peace protester. He said he had never been treated better by law enforcement officials than by the gardaí.

Mr McGillicuddy told the jurors the two men were sincere and honourable people and that couldn’t be disputed. But he told them to put sympathy aside and have regard to the law. He said the jury had to consider if the men had an honestly held belief that their actions were justified to protect other people.

He said the prosecution case was that they didn’t have any such lawful excuse and were there to make a political statement. Any qualms, claims, contentions, worries or concerns should have been reported to the authorities in the proper way, he said.

Mr Mayers' defence counsel, Michael Hourigan, said it was not some kind of political posturing but an honestly held belief that their actions on the day could save lives. He told the jurors that although the prosecution had claimed there were no arms on the plane, there was no practice of inspecting US military planes at Shannon.

Mr Hourigan said that when the jurors reach the age of 85, they may be doing something different than standing in the mud in a wet field in Clare. But he said that was what Mr Mayers felt he had to do to protect human life and he said there was a lot more to constitutional democracy than the letter of the law.

He urged the jurors to be the lamp and show that freedom lives by delivering verdicts of not guilty.

Mr Kauff’s defence counsel, Carol Doherty, said a person cannot be convicted of criminal damage in Ireland provided they can show they honestly believed their actions were lawful.

She pointed out that no airlines lost any money as a result of the airport closure and the delays were minimal.

She said her client had dedicated his life to peaceful protest. "People who go against the great can make a difference," she said. She said it was reasonable to assume the two men might have made a difference. The fact that their hope was not realised on this occasion did not mean the action was not justified.