Fifty aircraft were refused access to Irish airspace and airports last year over concerns they were carrying indiscriminate military hardware, it has been revealed.
The planes, classed as civilian and believed to be mostly US, sought permission to fly over the country, stop or refuel at Shannon but were denied on advice from government officials.
The Department of Transport said a total of 889 planes carrying guns and weapons applied to use Irish airports or airspace.
Some 808 permits were granted with the vast majority landing in Shannon while another 31 applications were cancelled.
No information has been revealed about the reasons why the 50 military contracted planes were denied access to Ireland or what exact type of munitions were believed to have been on board.
In 2015 the Department of Transport granted 584 exemptions for aircraft to land at Shannon with guns on board compared to 1,495 in 2007. There were 19 refusals.
The figures were released after anti-war group ShannonWatch said it had counted at least 730 US military flights coming through Shannon Airport last year - more than two planes every day owned by or operated on behalf of the US Air Force, Marines or Navy.
The figure is the highest number recorded by the group since it began daily monitoring in 2008.
Ed Horgan, spokesman for the campaign and a former Irish Army officer and United Nations elections' inspector, said: "These are the numbers recorded by ShannonWatch but they may not reflect the total numbers coming through.
"And the numbers surprised me."
More than 400 of the flights recorded by ShannonWatch were operated directly by the US Air Force, Navy or Marines. The rest were contracted troop carriers on civilian planes, some of which would be among the 889 planes granted exemptions to carry arms such as rifles without ammunition.
Among the planes recorded last year were 100 C-130s, also known as Hercules transporters, 15 four engine C17 Globemaster or C5 Galaxy transporters and 71 executive jets.
Mr Horgan said Ireland's approach to the use of airspace and airports as a neutral country should be compared with the attitude of Switzerland and Austria, two countries which routinely refuse US military access.
ShannonWatch last week called on Transport Minister Shane Ross to explain the presence of a plane operated on behalf of the US military that had stopped in Shannon for less than two hours before flying on to a Nato airbase in Turkey.
The Department of Foreign Affairs defended granting access to Irish air space and airports to the US military.
It insisted that the troops on board and the planes must be unarmed, with no cargo of arms, ammunition or explosives, not engage in intelligence gathering and not form part of military exercises or operations.
"Ireland remains strictly neutral and objective in applying the same strict conditions to the use of our airport by military aircraft belonging to all UN member states," a spokesman said.