Blocking Resolution: How External States can Prolong Civil Wars

The research argues that external states often intervene in civil wars to pursue objectives separate from those of internal combatants, which makes conflicts harder to resolve. Using Cox regressions on data from 1945 to 2004, the author finds that 'independent interventions' significantly increase war duration compared to 'non-independent' interventions. This is attributed to the introduction of additional demands that shrink the bargaining range, the difficulty of updating beliefs in multi-party conflicts, and the lower costs of fighting for external states compared to domestic actors.

• External states that intervene with an independent agenda—objectives separate from the goals of internal combatants—make civil wars substantially longer.
• The general academic finding that external interventions prolong civil war is primarily driven by the specific subset of cases where interveners pursue independent goals, rather than interventions in general.
• Independent interventions prolong conflict by increasing the number of combatants who must approve a settlement, which complicates bargaining by shrinking the 'bargaining range' of acceptable agreements.
• External states have less incentive to negotiate than internal actors because they face lower human and economic costs, as fighting occurs outside their own territory and they may exploit local resources to offset expenses.
• External states perceive lower benefits from negotiation because they cannot easily transition into domestic political movements or power-sharing arrangements, which are options available to domestic insurgents.
• Empirical analysis using Cox Proportional Hazards models shows that wars with clearly independent interventions have an almost 80% chance of surviving to 5,000 days, compared to 40% for wars with any intervention and 20% for wars with no intervention.
• Interventions coded as 'non-independent'—where the external state's goals align with an internal actor—have almost no statistically significant effect on the duration of the war.

APA

Cunningham, D. E. (n.d.). Blocking Resolution: How External States can Prolong Civil Wars. Peace Research Institute Oslo. https://cdn.cloud.prio.org/files/40f98eae-0a76-481d-8420-be2d3841d246/Blocking Resolution How External States can Prolong Civil Wars.pdf?inline=true

Chicago

Cunningham, David E. Blocking Resolution: How External States can Prolong Civil Wars. Peace Research Institute Oslo, n.d. https://cdn.cloud.prio.org/files/40f98eae-0a76-481d-8420-be2d3841d246/Blocking Resolution How External States can Prolong Civil Wars.pdf?inline=true.

Wikipedia

{{cite report |last1=Cunningham |first1=David E. |title=Blocking Resolution: How External States can Prolong Civil Wars |publisher=Peace Research Institute Oslo |url=https://cdn.cloud.prio.org/files/40f98eae-0a76-481d-8420-be2d3841d246/Blocking Resolution How External States can Prolong Civil Wars.pdf?inline=true |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{cunninghamndblocking, author = {Cunningham, David E.}, title = {{Blocking Resolution: How External States can Prolong Civil Wars}}, institution = {Peace Research Institute Oslo}, url = {https://cdn.cloud.prio.org/files/40f98eae-0a76-481d-8420-be2d3841d246/Blocking Resolution How External States can Prolong Civil Wars.pdf?inline=true}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }