The IRA's "Long War" was boosted by large donations of arms to them from Libya in the 1980s (see Provisional IRA arms importation) due to Muammar Gaddafi's anger at Thatcher's government for assisting the Reagan government's bombing of Tripoli, which had allegedly killed one of Gaddafi's children.

The IRA continued its bombing campaign. One of its most high profile actions was the Brighton hotel bombing on 12 October 1984, when it set off a 100-pound bomb in the Grand Hotel, Brighton, where politicians including Prime Minister Margaret Thatcher were staying for the Conservative Party conference. Five people were killed, including Conservative MP Sir Anthony Berry and the wife of Government Chief Whip John Wakeham, and thirty-four others were injured, including Wakeham, Trade and Industry Secretary Norman Tebbit and Tebbit's wife, Margaret.[91]

In the mid to late 1980s loyalist paramilitaries, including the Ulster Volunteer Force, the Ulster Defence Association and Ulster Resistance, imported arms and explosives from South Africa.[92] The weapons obtained were divided between the UDA, the UVF and Ulster Resistance, and led to an escalation in the assassination of Catholics, although some of the weaponry (such as rocket-propelled grenades) were hardly used.[citation needed] These killings were in response to the 1985 Anglo-Irish Agreement which gave the Irish government a "consultative role" in the internal government of Northern Ireland.