How Can Sustainable Peace Be Achieved?

In conversation with Thorsten Gromes

Thorsten Gromes

Dr. habil. Thorsten Gromes is a Project Leader and Senior Researcher at PRIF's Research Department Intra­state Conflicts. His research focuses on post-civil war societies and so-called humani­tarian military inter­ventions.

1. In your new book, “Sustaining Peace After Civil War”, you examined which factors make it more likely for civil wars to break out again or for peace to remain stable. Why is this question so important?

   When looking at conflicts around the world, it is striking that a large proportion of the ongoing conflicts are ones that have flared up again. In 2024, approximately every other armed conflict was a recurring one. Civil wars are a subgroup of armed intrastate conflicts. So, the world would be a lot more peaceful without the resurgence of conflicts.

2. What cases did you examine, and what methodological approach did you take?

   The project has examined 48 civil wars that ended between 1990 and 2009. Civil wars are defined as conflicts in which at least 1,000 people are killed over the course of the conflict as a result of fighting or attacks on civilians. I investigated whether the war had broken out again by 2012. Overall, the study employed a multi-method approach. Most of the individual analyses utilized both quantitative and qualitative methods.

   The entire study is based on a dataset that was created specifically for the project and is available to third parties. The individual analyses deal with different aspects of the question of when wars will break out again.

3. What are the most important results?

   The starting point for the study was the question of whether it was possible to reconcile different views on sustainable peace after civil wars. One view holds that lasting peace is guaranteed by military victories, while the other holds that it is guaranteed by political compromise. My hypothesis was that these research approaches might have a common basis, namely that civil wars do not break out again if the distribution of political benefits corresponds to the military balance of power between the parties to the conflict. However, if there is a mismatch between balance of power and political compromise, the assumption is that peace is in danger. That was the focus of the first part of the study. It has shown that while this connection exists, it is not as strong as I had suspected. The competing approaches could not be reconciled in this way.

   In the second part of the study, I examined the claim—often held in the literature—that military victories are more effective in ensuring a stable peace. The result was, however, that peace agreements are at least as effective in sustaining peace after civil war. Other ways of ending a war, in contrast, increase the likelihood that the war will break out again, for instance if the conflict ends with a mere ceasefire agreement, without resolving political issues.

   The third sub-study addresses precisely this issue and examines why ending wars with ceasefires proves to be particularly unstable. Two important reasons are: wars that end with ceasefires exhibit certain conflict characteristics that make it harder to establish peace. Additionally, mere ceasefires tend to result in fewer efforts to stabilize peace in the aftermath. We also see that political benefits and the military balance of power tend to diverge more after ceasefires than after victories or peace agreements.

4. In other words: Ceasefires do not necessarily cause wars to break out again, but they are often accompanied by conditions that make the resurgence of war more likely?

   They are often a reflection of existing problems, but they can also lead to a reduction in efforts to stabilize peace. For example, it has been observed that ceasefires alone tend to result in fewer peacekeeping missions and less civilian effort to consolidate peace. One reason is that in such situations external actors have less confidence in the stability of the peace.

5. And the other two parts of the study?

   The fourth analysis investigates the conditions under which peacekeeping troops actually succeed in securing peace. The study has shown that the characteristics of civil wars play a much more significant role than is typically assumed, for example by United Nations strategy papers. Peace missions are successful in advantageous contexts. The data also shows that when the context was especially difficult, peace was not sustained in any of the cases, despite the presence of peacekeeping forces.

   According to a view that used to be very prominent in civil war research, civil war breaks out again whenever the rebel side has the opportunity to do so. This is where the fifth part of my study comes in. It employs a method tailored to the hypothesis. The dataset also contains particularly informative data to assess whether the opportunity to resume the war is given, for example, whether a party to the conflict has retained separate armed forces or controls territory. Previous research, on the other hand, has used distant indicators to assess the financial or military feasibility of renewed war. My findings showed that, while feasibility does make a recurrence more likely, no deterministic relationship can be observed.

1. Well, that’s almost good news for peace.

   The implications for policymakers are interesting. Those who believe that only feasibility matters will also argue that any efforts to appease the parties to the conflict and reach compromises are unnecessary. Essentially, you would only have to ensure that one party loses the means to continue fighting. My study, on the other hand, shows that peace is often sustained even when the feasibility of renewed rebellion is very high, provided that the political concerns of the parties to the conflict have been addressed.

2. Based on this project, you also wrote a widely noted PRIF Spotlight on so-called “conflict myths.” What exactly are conflict myths?

   I define conflict myths as claims about conflicts that we encounter time and again – in politics, in the media, in academic discourse, but also in every-day conversation. I call them “myths” because they are assumptions that seem plausible at first glance and may contain a kernel of truth but are then exaggerated to a such an extent that they become false. So, they are not conscious lies but misinterpretations of conflicts. Another characteristic is that they do not make statements about a specific conflict but rather argue across different cases. If one follows the logic of these myths, it can also have political consequences.

3. Can you give an example, and explain what the myth is in this case, and perhaps also where the kernel of truth lies?

   One conflict myth that has been particularly prominent in recent years is this saying: “Every war ends at the negotiating table.” Or similarly: “There is no military solution to the conflict.” That is simply not true. If we look at the data, we see that, for example, since World War II, about one third of all conflicts have ended with a military victory for one side. Only one in four conflicts ended with a negotiated agreement.

   There are wars that cannot be won. In such cases, negotiating is the only solution. But in many conflicts, the situation is different. One might wish that many of these conflicts would have ended through negotiation. But saying that they will inevitably end this way is a misrepresentation of reality.

4. In your current research project, you are examining so-called humanitarian military interventions. Can you elaborate on what it is about?

   Humanitarian interventions are defined as situations in which a state, a coalition of states, or an international organization sends troops to a country in conflict with the stated aim of protecting the people there from violence. In a previous project here at PRIF, we compiled a dataset documenting these missions since World War II. We are now researching the effects of humanitarian military interventions and the conditions under which various outcomes occur. When are they successful in resolving or containing conflicts? When they fail, in which cases do conflicts continue or even escalate?

1. Can you share any preliminary results yet?

   Lucas Kori Leonhard and I recently published the results of our co-authored sub-study in International Peacekeeping. We looked into the question of when humanitarian interventions actually occur and when they do not. Only one in eleven armed conflicts results in a humanitarian military intervention. Multiple factors are relevant; on the one hand, the extent of destruction and human suffering. The more deaths there are in a conflict, the higher the likelihood of a humanitarian intervention. On the other hand, chances of success and risks play a large role. We have found that three quarters of all humanitarian military interventions exhibit this combination of characteristics: a high level of urgency and plausible prospects for success. Although humanitarian military interventions generally are an exception, there is a pattern that guides them.

2. What do you want to research next?

   The project on humanitarian military interventions will continue for a while. After that, I plan to pursue a project on the concept of “conflict maturity,” which is highly prominent in research and has also influenced international diplomacy. Interestingly, there is a lack of comparative studies on this topic. That is where I would like to step in. (ewa)