The Irish Government officially had little role in the Troubles. Having said that, they continued to politically and diplomatically demand the reunification of Ireland, giving political cause and motivation to the IRA. If reunification could not be achieved, then the Irish government wanted to see power sharing in the North of Ireland.

In the early days of the Troubles, in 1969, the Irish cabinet discussed a military incursion North of the border, or the establishment of a provisional IRA in the North to agitate for the reunification of Ireland. Available records indicate that both these options were rejected.

In 1970, a quarter of the Irish cabinet was dismissed or resigned because they were caught up in a scandal concerning the importation and movement of weapons north for the IRA. The subsequent trial saw the charges levelled against the politicians concerned dropped.

Another key event in Irish-British relations came shortly after Bloody Sunday in 1972, when 26 unarmed catholic civil rights protesters were shot at and killed by British troops. The Irish government declared a day of mourning, and in Dublin riots broke out, leading to the burning down of the British embassy. To some extent, this event caused great concern in the Irish government that the Troubles in the North could spill over and cause civil war in the South.

This concern meant that, for example, in 1974, when loyalist paramilitaries conducted a bombing campaign in Dublin and Monaghan, killing 34 Irish citizens, the Irish government did not call a day of mourning, and went so far as to not pursue those responsible for the bombings, despite receiving intelligence from the British about their whereabouts, for fear that loyalist paramilitaries would turn their attention to the Republic of Ireland.

Irish government also consistently refused to extradite leading republican paramilitaries to the UK after they had taken up residency in the Republic of Ireland perhaps out of fear that the IRA would increase its activities south of the border, though this was, with good reason, interpreted also as a political standpoint.

That is the official side of the story. In 2013, after years of rumour and speculation, an Irish government inquiry, the Smithwick tribunal, confirmed that there had been collusion between the Irish Garda Síochána (the police service) and the IRA in the murder of members of the RUC. This was again revealed in 2018, when declassified state documents confirmed that the Gardaí had tipped the IRA off about the whereabouts of the British ambassador.

In 2014, the former head of IRA intelligence, Kieran Conway, alleged that not only was there collusion between the IRA and the Gardaí, but that members of the political elite, including members of the Irish government, journalists and bankers, aided the IRA by smuggling weapons or providing safe houses for paramilitaries or by laundering money.

More recently, historian Gearóid Ó Faoleán gathered various strands of evidence from both Irish and British documents to show the extent to which the Republic of Ireland provided support to the IRA. In his book A Broad Church, he discusses how the IRA conducted bank robberies in the Republic of Ireland in the 1970’s to fund their campaign with general support from the populace, and with a failure of the Gardaí to prosecute. He confirms general political support from all mainstream political parties in the Republic of Ireland in the 1970’s with direct support provided by leading politicians. He discusses logistical support to purchase explosives, smuggling of other weapons, training of IRA cadets by the former members Irish Defence Forces, with training camps widely known about without intervention by the Gardaí.

The Irish government has, to date, refused a further inquiry into these allegations.

Despite the distinctly chilly relations between the Irish and British government in the 1970’s, there was a distinct defrosting in the relationship in the 1980s. The Irish government established a New Ireland Forum in 1984 which made several recommendations to allow for the end of Troubles. Although the recommendations were rejected by the British government, they gave the Irish government political mandate to pursue a solution to the Troubles rather than support for nationalist and republican groups in Northern Ireland. They also gave leverage to the Irish government in negotiations for the Anglo-Irish agreement in 1985. The relationship between the governments, at least in relation to the Troubles was again reinforced by the Downing Street declaration in 1992, and the Irish government was a key party in the Good Friday agreement in 1998.