This thesis aims to explain how the involvement of secondary parties affect the duration of intrastate armedconflicts. It argues that the acquisition of secondary support in favor of rebel groups is likely to lead to an extended duration of intrastate armed conflict. By granting a relatively weaker rebel group secondary support, a secondary party ought to directly alter the balance of power and capabilities in benefit for the rebels. The secondary party could thereby be able to level the balance of capabilities between a government and a rebel group, creating a situation in which the, at first, stronger government now have to face a rebel group capable of surviving longer. Using a structured focused comparison on two cases, the results find secondary support in the form of funding or economic support given to relatively weak rebels to be an important influence on extending the duration of intrastate armed conflicts. Nonetheless, further research might have to be made in order to fully understand the even more detailed mechanisms behind the strong influences of economic secondary support on conflict duration.

The answer to if peacekeeping is successful or not is still debated. The focus has mostly been on internal characteristics of peacekeeping missions. While external factors, have been largely overlooked. This thesis aims to explore the effects external involvement in intrastate conflicts may have on the success of peacekeeping deployment. It poses the following research question: how does foreign state sponsorship to rebel groups affect the success of peacekeeping operations? The main argument made is that the causal mechanisms presented for why peacekeeping operations are effective, do not have an effect on the sponsors and their incentive to stop fighting. Hence, it is hypothesized that peacekeeping operations are less effective in decreasing the duration of intrastate armed conflict when rebel groups are sponsored by foreign states. The argument is tested using a discrete-time survival analysis and Cox proportional hazard models on all intrastate conflicts between 1970-2017, and foreign state sponsorship is treated as an interaction effect. The findings did not support the hypothesis but rather suggest that the presence of peacekeepers has a dominant positive conflict-intensity reducing effect. These results scratch the surface of what the effects external involvement may have on peacekeeping success and indicate that peacekeeping is successfully undermining sponsorship.