The Irish parliament's Joint Committee on Justice called the attacks an act of international terrorism involving British state forces.

[10] Two of the victims were foreign: Antonio Magliocco, an Italian man, and Simone Chetrit, a French Jewish woman whose family had survived the Holocaust.

Almost ninety minutes later, at about 18:58, a fourth car bomb (weighing 68 kilograms (150 lb)) exploded in the centre of Monaghan town, just south of the border with Northern Ireland.

[20] The bomb site, which was about 270–370 metres (890–1,210 ft) from the Garda station, was preserved by a roster of eight Gardaí from 19:00 on 17 May until 14:30 on 19 May, at which time the technical examination of the area had been completed.

[20] It has been suggested that the Monaghan bombing was a "supporting attack"; a diversion to draw security away from the border and thus help the Dublin bombers return to Northern Ireland.

[22] Rescuers, feeling that help was not coming fast enough, lifted the dead and wounded, wrapped them in coats and bundled them into cars to get them to the nearest hospital.

[22] Paddy Doyle of Finglas, who lost his daughter, son-in-law, and two infant granddaughters in the Parnell Street explosion, described the scene inside Dublin's city morgue as having been like a "slaughterhouse", with workers "putting arms and legs together to make up a body".

[22] Garda officers were sent to Connolly Station, Busáras, Dublin Airport, the B&I car ferry port, and the mail boat at Dún Laoghaire.

[24] Martha O'Neill was not caught up in the attack, although two of their children were seriously injured in the bombing; one of them, a four-year-old boy, suffered severe facial injuries.

[29] Taoiseach Liam Cosgrave, of Fine Gael, recorded his disgust and added:[30] The blood of the innocent victims of last Friday's outrage—and of the victims of similar outrages in the North and in England—is on the hands of every man who has fired a gun or discharged a bomb in furtherance of the present campaign of violence in these islands—just as plainly as it is on the hands of those who parked the cars and set the charges last Friday.

In our times, violence cannot be contained in neat compartments and justified in one case but not in another.The opposition leader Jack Lynch, of Fianna Fáil, was "sickened" by the "cruel" events, and also widened the question of blame:[30] Every person and every organisation which played any part in the campaign of bombing and violence which killed and maimed people and destroyed property in Belfast, Derry or any other part of our country and indeed in Britain over the past five years, shares the guilt and the shame of the assassins who actually placed these bombs on the streets of Dublin and Monaghan last Friday.In secret memos, Arthur Galsworthy, British Ambassador to the Republic of Ireland, noted the reactions in Dublin immediately after the bombings.

He reported that Minister for Foreign Affairs Garret FitzGerald told him that "the government's view was that popular hostility appeared to be directed more against the IRA", and that[31] There is no sign of any general anti-Northern Protestant reaction ...

[32] Richard Eder at The New York Times reported on 19 May 1974 at the scene two days after the bombing: The tendency here not to think about the problems of the North and the consequent lack of any strong public pressure to take action against the gunmen operating from the republic's territory comes from something more complex than complacency.

Partly it was the pessimistic conclusion that only a final armed showdown between northern Protestants and Roman Catholics would solve the problem, and the natural tendency to think as little as possible about such a terrifying and dangerous prospect.

[33] The following day, Eder reported the bombing was carried out by loyalist paramilitaries who "wanted to give this predominantly Roman Catholic country a taste of the kind of violence served on the North by the Provisional wing of the IRA.

[39][40] The documentary also suggested that British Army officer Robert Nairac, a member of the covert Special Reconnaissance Unit/14 Intelligence Company, may have been involved.

The narrator said: "We have evidence from police, military and loyalist sources which confirms [...] that in May 1974, he was meeting with these terrorists, supplying them with arms and helping them plan acts of terrorism".

In contrast to the scenario painted by the programme, it would have been unnecessary and indeed undesirable to compromise our volunteers anonimity [sic] by using clandestine Security Force personnel, British or otherwise, to achieve [an] objective well within our capabilities.

[45] Two motions were passed unanimously by Dáil Éireann in 2008 and 2011, urging the British Government to make the documents available to an independent, international judicial figure for assessment.

It was also alleged that the Fine Gael/Labour government caused or allowed the Garda investigation to end prematurely, for fear that the findings would play into the hands of republicans.

Subsequent reports by Henry Barron into the Miami Showband massacre, the killing of Seamus Ludlow, and the bombing of Keys Tavern found evidence of extensive collusion with the same UVF members, amounting to "international terrorism" on the part of British forces.

In an August 1975 letter to Tony Stoughton, chief of the British Army Information Service in Northern Ireland, Wallace writes:There is good evidence the Dublin bombings in May last year were a reprisal for the Irish government's role in bringing about the [power sharing] Executive.

Craig's people believe the sectarian assassinations were designed to destroy Rees's attempts to negotiate a ceasefire, and the targets were identified for both sides by [Intelligence/Special Branch].

[66]In his evidence to the Barron Inquiry, Wallace argued that the security forces had so thoroughly infiltrated the UVF that they would have known such a huge bombing operation was being planned and who was involved.

[68] Barron noted that Wallace's August 1975 letter was "strong evidence that the security forces in Northern Ireland had intelligence information which was not shared with the Garda investigation team.

Wallace claims the real reasons for his dismissal were his refusal to continue working on the Clockwork Orange project, and his discovery that the security forces were involved in a child sex abuse ring.

However, Barron found: "The visit by Holroyd to Garda Headquarters unquestionably did take place, notwithstanding former Commissioner Garvey's inability to recall it".

[85] David Ervine, a member of the UVF sentenced to 11 years for possession of explosives in November 1974, dismissed allegations of collusion in the Dublin and Monaghan bombings as "sheer unadulterated nonsense", saying, "there comes a point when the concept insults me, insomuch as that a Provo could lie in bed and with a crystal ball... could pick their targets but a Prod could only do the same if there was an SAS man driving the car".

"[87]In May 2024 Iain Livingstone, head of Operation Denton, said that there was no doubt of collusion between the Glenanne gang and British authorities in the Dublin and Monaghan bombings.

In his 2022 memoir Surrender: 40 Songs, One Story, Bono disclosed that at the time he and a friend often went to browse at the Dolphin Discs record store on Talbot Street, near where the bombs went off.