Despite the successful decommissioning of weapons from the largest paramilitary organizations, several dissident groups on both sides stayed armed and continued violent activity. Even in the IICD’s final report, they commission acknowledged that militants who did disarm could not always be sure they had secured all weapons in their inventory, especially considering how often splinter factions formed. The Provisional IRA faced considerable trouble in keeping its hardline members in order as they pivoted towards political participation. In public statements, the IRA continued to emphasize their commitment to Irish reunification, and an internal document promoting the “TUAS” strategy (tactical use of armed struggle) tried to reassure members that negotiations opened a new avenue for fulfilling their goals. Following the Provisional IRA’s ceasefires in the 1990s, two dissident groups split off to wage their own campaigns: The Continuity IRA and the Real IRA. The most significant operation carried out by dissidents was the Real IRA’s attack in the small town of Omagh. On August 15, 1996, just a few months after the Good Friday referendum, the Real IRA detonated a car bomb during a civic festival. Twenty-nine people died, with many more injured, making it one of the deadliest single attacks of the Troubles.
While the Provisional IRA and Irish National Liberation Army both eventually put their guns and disbanded, the CIRA and RIRA never agreed to decommission. Since neither group has disbanded to this day, precise information about their numbers and arms is limited. Both groups, however, are estimated to have members numbering only in the dozens. Both groups also probably retrieved a limited number of weapons from Provisional IRA dumps before decommissioning, including a small number of handguns, rifles, machine guns, Semtex explosives and their detonators. Unaccounted-for weapons have been a persistent issue. In one notable case from 2016, people walking in a public park in the town of Larne stumbled upon a cache of explosives including landmines, Claymore mines, pipe bombs, detonators, and ammunition.
Dissident groups have continued illegal activity in the last two decades, including murdering political opponents and numerous attempted bombings. According to the PSNI, between April 1998 and April 2018 a total of 158 people have been killed in “security-related killings,” including the Omagh attack. While this is a large number, it still represents a significant reduction from the period between 1968 and 1998 in which almost 3,600 people died. It is also notable that most of the violence since 1998 has been intra-communal, with republican groups being mostly responsible for Catholic deaths and loyalists groups accounting for most of the Protestant killings. This suggests that recurring sectarian violence has been greatly reduced, and a resurgence of violence like that seen during the Troubles is unlikely at this time.
Ultimately, continuing violence in Northern Ireland did not ultimately derail the peace process. Outrage over Omagh was nearly unanimous across both republican and loyalist groups, and the incident put more pressure on all parties to cooperate with the Agreement and decommission. The widespread support for the peace deal among both Catholics and Protestants meant that paramilitaries faced increasing difficulties in recruitment and support from the broader population, and would not be able to wage a significant campaign going forward. Political scientists studying the ends of civil wars have observed that acts of terrorism during negotiations can not only spoil the peace process, but can also shorten the amount of time before a civil conflict reignites. The lack of large-scale violence following Omagh suggests that the Northern Irish experience serves as an exception to this rule. Even though the IICD could not decommission all paramilitary weapons, the disarmament of the major militant groups meant that the smaller dissidents could not pose a long-term threat to the stability of peace in Northern Ireland.
 “Final Report of the Independent International Commission on Decommissioning,” Accessed 4 April 2022. https://cain.ulster.ac.uk/events/peace/decommission/iicd040711.pdf.
 “Republican Movement (1994), The ‘TUAS’ Document,” CAIN Archive, CAIN Web Service, Accessed 4 April 2022. https://cain.ulster.ac.uk/othelem/organ/ira/tuas94.htm.
 English, Armed Struggle, 296.
 Martin Melaugh, “Estimates of the Strength of Paramilitary Groups,” CAIN Archive, CAIN Web Service, Accessed 22 April 2022. https://cain.ulster.ac.uk/issues/violence/paramilitary2.htm.
 Henry McDonald, “Antrim weapons cache is most significant arms find in years, says PSNI,” The Guardian, 17 May 2016. Accessed 22 April 2022. https://www.theguardian.com/uk-news/2016/may/17/antrim-weapons-cache-is-most-significant-arms-find-in-years-says-psni.
 “Timeline of Dissident Activity,” BBC News, 10 September 2019. Accessed 22 April 2022. https://www.bbc.com/news/uk-northern-ireland-10866072.
 Paul Nolan, ‘Post-conflict’ Northern Ireland is still plagued by political violence,” The Irish Times, 23 April 2018. Accessed 22 April 2022. https://www.irishtimes.com/news/crime-and-law/post-conflict-northern-ireland-is-still-plagued-by-political-violence-1.3470229.
 English, Armed Struggle, 379.
 Paul Nolan, “‘Post-conflict’ Northern Ireland is still plagued by political violence,” https://www.irishtimes.com/news/crime-and-law/post-conflict-northern-ireland-is-still-plagued-by-political-violence-1.3470229.
 MacGinty, Guns and Government, 45.
 Michael G. Findley and Joseph K. Young, “Terrorism, Spoiling, and the Resolution of Civil Wars.” The Journal of Politics, Vol. 77 No. 4 (2015), 1115-1128.