[9] The organisation's number of employees and budget are classified, with a further 150-200 operatives in the Army Ranger Wing (ARW), who can conduct missions at the behest of Military Intelligence.

[1] The latter is rumoured to house sophisticated modern technology for espionage; the building was completed in 2010 after a number of years of construction, at a cost of €30 million.

Staff actively monitor relevant political, economic, social and military situations globally to produce intelligence reports and strategic studies to support operations.

The Directorate is responsible for conducting background checks of all Defence Forces personnel through close cooperation with the Garda National Vetting Bureau (GNVB).

This includes identifying, monitoring and assessing possible threats to the state and Irish national interests at home and abroad, be it by hostile intelligence services, terrorist groups and/or criminal organisations.

Counter-intelligence forms a large part of the section's remit, in addition to fulfilling counter-terrorist, counter-subversion, counterinsurgency, counter-sabotage roles, and physical security of critical infrastructure.

During this period, G2 intercepted German naval and aerial communications through listening stations located across Ireland, sharing the information with Allied forces.

[23] Under Colonel Daniel "Dan" Bryan, Director of Intelligence, G2 apprehended all thirteen Nazi spies sent to Ireland, notably Hermann Görtz, and broke German codes during the war, under the supervision of cryptologist Richard J. Hayes.

[26][27] In 1970, the Arms Crisis and subsequent trial engulfed the state in a political scandal in which Irish Army intelligence officer Captain James Kelly was implicated in an unauthorised covert operation with the knowledge of Minister for Finance Charles Haughey and Minister for Agriculture and Fisheries Neil Blaney whereby £50,000 of a secret Irish government humanitarian fund of £100,000 (which had been set-up to help refugees fleeing Northern Ireland) was diverted and used to illegally import and smuggle arms and ammunition for the Provisional Irish Republican Army (IRA).

The Garda Special Branch became aware of the unsanctioned operation and informed Minister for Justice Mícheál Ó Móráin and Taoiseach Lynch, who were slow to take action.

This resulted in Ministers Haughey (who later became Taoiseach) and Blaney being sacked from their posts, Captain Kelly was forced to resign, and the subsequent trial of all three in which the case collapsed and they were cleared of charges.

Declassified intelligence files marked "Confidential" released at the end of 2019, after 30 years, show Irish government concerns over the possibility of British nuclear weapons in Northern Ireland.

Colonel L Buckley, then Director of Intelligence briefed Peter Barry, then foreign minister, in November 1983 on the possibility of British/NATO nuclear missiles on the island of Ireland.

[30] A separate file marked "Secret" from June 1985 shows that Irish military intelligence carried out reconnaissance on a British Army installation at Forkhill, Armagh (Northern Ireland) after it received information of "strong rumors" from locals that it was being converted into a nuclear facility.

Materials had been brought into the base in night convoys but this was done for security reasons and it noted that there were underground facilities at Forkhill but that these were for accommodation and protection in the event of a mortar attack.

Military intelligence did, however, have a reservation that Forkhill was "now on a microwave communications network which would have a Nato function in relation to possible nuclear attack".

Following the intervention of Irish, British and American governments, Rory Carroll was released unharmed days later and returned safely to Dublin.

[34] The Directorate receives intelligence reports from civil servants posted at Irish diplomatic missions overseas, via the Department of Foreign Affairs (DFA).

[35][36] The Defence Forces and Garda Síochána provide security briefings to Department of Foreign Affairs employees and their families regarding potential terrorist attacks in host countries they are posted to.

[38] There was reported to be significant dissatisfaction within J2 and the higher levels of the Defence Forces with the government's decision, as intelligence officers believed their experience put them in the best position to extract Smith and her child safely and quietly, rather than the DFA or Gardaí.

[41] Military Intelligence and the Garda Special Detective Unit's Middle Eastern Desk are tasked with monitoring potential jihadists in Ireland and Irish citizens who fight abroad in warzones – specifically Syria and Iraq – for Muslim extremist organisations such as the self-proclaimed "Islamic State".