Irish military intelligence was convinced Benbradagh had been equipped to store nuclear weapons by the early 1980s, according to confidential files newly released by the National Archives in Dublin.
Declassified correspondence between Óglaigh na hÉireann's Director of Intelligence Col. L. Buckley and the Minister of Foreign Affairs of the day, Peter Barry, dated, November 1983, show the Irish authorities were concerned nuclear weapons could be stored inside the Dungiven mountain.
A 'confidential' note states: “Benbradagh NE of Dungiven has underground facilities, which were originally constructed by US forces for the storage of conventional high explosives but were subsequently redesigned and are understood to be suitable for the storage of nuclear weapons if so required."
The correspondence reveals Dublin was concerned British aircraft armed with nuclear bombs could be accommodated elsewhere in County Derry.
Col. Buckley informed Mr. Barry that RAF Ballykelly could “accommodate all UK and NATO aircraft including the Vulcan bomber".
He further warned that it was difficult for Irish intelligence to keep track of all British manoeuvres in the North and to “confirm the movements or emplacement of UK/NATO surface ships, submarines, aircraft or nuclear devices or their supporting systems in and around the territory of Northern Ireland".
A separate tranche of newly released files from 1990 show concerns were also raised about the possibility of the dumping of chemical weapons off Donegal.
In June 1990 the Donegal Southwest T.D. and Minister for the Gaeltacht Pat 'the Cope' Gallagher received a letter from a concerned constituent who claimed the 'big belligerents' had been dumping weapons off the North West coast "as they have done for the past forty-odd year".
Deputy Gallagher wrote to the Minister for Foreign Affairs Gerard Collins asking him to comment on the “dumping of chemicals by foreign countries off the coast of Donegal”.
In response to the constituent's concerns the department said: "We are not aware of any proposals to dump chemical weapons off Donegal, or of any allegations that such dumping has taken place in the past. Chemical weapons are normally destroyed by burning, rather than by dumping at sea."
The revelations contained in the state papers come after the British Ministry of Defence (MoD) confirmed to the 'Journal' last year that three sites in Derry, Clady and Omagh, formerly used by the military for the storage of chemical warfare agents, were subject to a contamination review initiated in the 2000s.
‘Project Cleansweep’ was set up the MoD in 2007.
“Project Cleansweep initially carried out a desk study of a large number of sites across the UK where there was evidence of some prior connection to chemical warfare agents,” the MoD said.
Derry, Clady and Omagh were not considered of particular concern, however, and the British military authorities concentrated on a short-list of 14 sites all of which were in Britain and mainly in private ownership.