The IRA initially focused on defence of Catholic areas, but it began an offensive campaign in 1970 that was aided by external sources, including Irish diaspora communities within the Anglosphere, and the Palestine Liberation Organization and Libyan leader Muammar Gaddafi.

The IRA's armed campaign, primarily in Northern Ireland but also in England and mainland Europe, killed over 1,700 people, including roughly 1,000 members of the British security forces and 500–644 civilians.

The Provisional IRA declared a final ceasefire in July 1997, after which its political wing Sinn Féin was admitted into multi-party peace talks on the future of Northern Ireland.

[61] The Provisional IRA issued their first public statement on 28 December 1969,[4] stating: We declare our allegiance to the 32 county Irish republic, proclaimed at Easter 1916, established by the first Dáil Éireann in 1919, overthrown by force of arms in 1922 and suppressed to this day by the existing British-imposed six-county and twenty-six-county partition states ... We call on the Irish people at home and in exile for increased support towards defending our people in the North and the eventual achievement of the full political, social, economic and cultural freedom of Ireland.

[87] The strategic aim behind the bombings was to target businesses and commercial premises to deter investment and force the British government to pay compensation, increasing the financial cost of keeping Northern Ireland within the United Kingdom.

[125][126] By July the Army Council was concerned at the progress of the talks, concluding there was no prospect of a lasting peace without a public declaration by the British government of their intent to withdraw from Ireland.

[144] The IRA's new multi-faceted strategy saw them begin to use armed propaganda, using the publicity gained from attacks such as the assassination of Lord Mountbatten and the Warrenpoint ambush to focus attention on the nationalist community's rejection of British rule.

[152] In October 1984 they carried out the Brighton hotel bombing, an assassination attempt on British prime minister Margaret Thatcher, whom they blamed for the deaths of the ten hunger strikers.

[155] The plans, modelled on the Tet Offensive during the Vietnam War, relied on the element of surprise which was lost when the ship's captain informed French authorities of four earlier shipments of weapons, which allowed the British Army to deploy appropriate countermeasures.

[158] Sinn Féin president Adams was in contact with Social Democratic and Labour Party (SDLP) leader John Hume and a delegation representing the Irish government, in order to find political alternatives to the IRA's campaign.

[159] As a result of the republican leadership appearing interested in peace, British policy shifted when Peter Brooke, the Secretary of State for Northern Ireland, began to engage with them hoping for a political settlement.

[184] On 9 February 1996 a statement from the Army Council was delivered to the Irish national broadcaster Raidió Teilifís Éireann announcing the end of the ceasefire, and just over 90 minutes later the Docklands bombing killed two people and caused an estimated £100–150 million damage to some of London's more expensive commercial property.

[185][186] Three weeks later the British and Irish governments issued a joint statement announcing multi-party talks would begin on 10 June, with Sinn Féin excluded unless the IRA called a new ceasefire.

[n 18][200] This was partly triggered by Stormontgate—allegations that republican spies were operating within the Parliament Buildings and the Police Service of Northern Ireland (PSNI)[n 19][202]—and the IRA temporarily broke off contact with de Chastelain.

[207] The IRA invited two independent witnesses to view the secret disarmament work, Catholic priest Father Alec Reid and Protestant minister Reverend Harold Good.

[235][236] The mortars used a variety of different firing mechanisms including delay timers, this combined with the disposable nature of the weapons allowed IRA volunteers to reduce the risk of being arrested at the scene.

[n 23][243] Due to negative publicity after the Abercorn bombing, the IRA introduced a system of telephoned coded warnings to try to avoid civilian casualties while still causing the intended damage to properties and the economy.

[279] Its main responsibilities were support activities for Northern Command, such as importation and storage of arms, providing safe houses, raising funds through robberies, and organising training camps.

[10] Journalists Eamonn Mallie and Patrick Bishop state roughly 8,000 people passed through the ranks of the IRA in the first 20 years of its existence, many of them leaving after arrest, retirement or disillusionment.

[344][345] In addition, Irish American support for the Republican cause began to weaken in the mid-1970s and gradually diminished in the 1980s due to bad publicity surrounding IRA atrocities and NORAID.

Gearóid Ó Faoleán wrote that "[i]n 1972, inclement weather forced a light aeroplane to reroute to Shannon Airport from Farranfore in County Kerry, where IRA volunteers had been awaiting its arrival.

[363] Former MI5 agent Willie Carlin said that one of the main reasons why the IRA Army Council did not attack Scotland during the conflict was because doing so would reduce support from Scots and have a negative impact on its fundraising and other activities there.

[371][372] The Irish Minister for Justice, Equality and Law Reform stated the IRA was to be paid up to $35 million to train FARC in bomb-making techniques, including shaped charges, propane bombs, landmines and the construction of mortars.

[374] Since the Troubles began, the IRA was involved in criminal activities such as robberies, counterfeiting, protection rackets, kidnapping for ransom, fuel laundering and cigarette smuggling in order to fund its armed campaign.

[380][381] In April 1987, RUC chief constable John Hermon told government ministers at the Anglo-Irish Intergovernmental Conference that "[i]t costs the IRA £2-£3 million per year to maintain its activity.

It identified extortion, fuel laundering, rum-running, tobacco smuggling, armed robbery, and counterfeiting in Ireland and Britain as the primary sources of funding for both Republican and Loyalist militants throughout and after the Troubles, while "the sums involved [from overseas] [were and] are comparatively small".

[389] Adams said at Sinn Féin's 2005 ard fheis "There is no place in republicanism for anyone involved in criminality", while adding "we refuse to criminalise those who break the law in pursuit of legitimate political objectives".

[402] Protestants in the rural border areas of counties Fermanagh and Tyrone, where the number of members of the security forces killed was high, viewed the IRA's campaign as ethnic cleansing.

[406][407] The RUC found it difficult to operate in certain nationalist neighbourhoods and only entered in armoured convoys due to the risk of attack, preventing community policing that could have occurred if officers patrolled on foot.

[n 36][441][442] In March 1999 the IRA apologised for the "prolonged anguish" caused to the families of the Disappeared, and stated it had identified the burial places of nine people,[443] including the most high-profile victim, Jean McConville, a Catholic civilian and widowed mother-of-ten.