UN involvement and civil war peace agreement implementation

Many studies argue that third-party guarantees, such as those of the United Nations, increase the chances that belligerents will sign peace agreements, but it is unclear how third-party involvement affects the implementation of such agreements. We unpack the relationship between UN involvement and peace agreement success by focusing on the risk of defections during the peace accord implementation phase. We argue that two types of commitment problems, namely involuntary and voluntary defections, emerge from the characteristics of the peace process itself as well as from new opportunities available to rebel groups. We expect that shifts in relative power and polarized voting lead to lower implementation scores overall, but that the deployment of UN troops has a mitigating effect, thereby increasing the prospects of sustainable peace agreements. Using data from the Peace Accords Matrix Implementation Dataset from 1989 to 2010 and personnel commitments to UN peacekeeping operations, we find evidence that large UN missions are better placed to support the implementation and longevity of the peace process.