Since early December 1989, the British Army had been on alert in and around County Tyrone after a credible threat was made by a suspected member of the IRA about an imminent attack.

[2] While British officials focused on members of the IRA from County Monaghan, in the Republic, supported by others from Clogher, County Tyrone,[1] author Ed Moloney asserts that the culprit was a flying column made up of IRA volunteers from different brigades, commanded by the East Tyrone Brigade's Michael "Pete" Ryan, who himself was shot dead in 1991 in the Coagh ambush.

Another key role was to scan the terrain for potential enemy ambushes and to block the IRA getaway by landing reinforcements on their escape route.

[4] At 16:30, a local witness heard 50 to 60 shots fired, then she saw the helicopter skimming over an open field just north of the border,[6] near Derrygorry, in the Republic.

[4] After this and other attacks on security forces along the border in 1990, especially against permanent vehicle checkpoints, the troops were issued with .50 Browning machine guns and M203 grenade launchers.

[10] By 1992, the use of long-range weapons by the Provisionals, like mortars and heavy machine-guns, had forced the British Army to build its main checkpoints along the border one to five miles within Northern Ireland to avoid assaults launched from inside the Republic.

[11] In 1993, two helicopters were fired at in different circumstances, one of them with heavy machine guns on 8 January at Kinawley after a mortar attack on a British Army outpost,[14] and the other with automatic rifles on 12 December near Fivemiletown, County Tyrone, after an ambush where two RUC officers from Clogher barracks were killed.