That is according to new figures provided by the Minister for Justice, Frances Fitzgerald, and the Minister for Defence, Simon Coveney, who confirmed that the spend on the Army and Gardaí in providing security to the US military at Shannon last year topped €1.4m.

Between 2003 and 2009, the Garda and army bill to the State for protecting the US military at Shannon stood at almost €18m. Since 2000, more than 2.25m US troops have passed through Shannon.

In a written Dáil reply to Independent TDs Clare Daly and Mick Wallace, Ms Fitzgerald confirmed that the State last year spent €1.2m relating to the gardaí providing protection at Shannon, while the army bill came to €180,000.

Asked to provide the costs of protecting the US military by both TDs, Ms Fitzgerald replied: “The deployment of Gardaí at Shannon Airport is aimed primarily at protecting the safety of passengers and other people working at and using the airport.

“I am informed by the Garda Authorities that the cost to An Garda Síochána of deployment at Shannon airport was €1.23m in 2015 comprising salaries and other pay and non-pay related expenditure. In his reply to the two deputies, Minister Coveney confirmed the Army spend at €180,814 for the year.”

Minister for Justice, Frances Fitzgerald

Mr Coveney said the army costs incurred comprise payment of Security Duty Allowance, provision of rations, and fuel.

The army costs work out at, on average, €3,461 per week, while the average weekly Garda costs work out at €23,673.

According to figures provided by Ms Fitzgerald, the highest monthly spend last year was in October, when €123,837 was spent on Garda security at Shannon.

Ms Daly and Mr Wallace appeared in court on Friday as witnesses for 70-year-old peace activist Ed Horgan,where a judge dismissed a charge that Dr Horgan illegally entered a restricted area at Shannon Airport when trying to inspect four military US Hercules C-130 aircraft last year.

In the witness box, Ms Daly presented to Judge Aeneas McCarthy more than 100 Dáil questions on the military use of Shannon while Mr Wallace told the court “it was very difficult to get our Dáil questions answered”.

In the case, Dr Horgan was at Shannon Airport to board a London bound flight where he was due to attend a peace conference on April 18, 2015. Dr Horgan told the court that, as he was waiting to board the aircraft, he saw four US military Hercules aircraft on the airfield being guarded by an Irish army jeep. Dr Horgan said he had a boarding pass to be airside and walked for a couple of minutes on the airport apron towards the military aircraft before he was intercepted.

In evidence of what Dr Horgan said under caution, Sgt Denis Lavin said that Dr Horgan told him: “I went to search the four military aircraft because I have no doubt that they are carrying weapons and explosives in a breach of Irish neutrality and for those reasons I was fully justified to be at that location in the airport.”

Dr Horgan said that he has made more than 100 complaints to Shannon gardaí asking them to search US military planes at Shannon.