You can includ GDP,Inflation, population growth, natural ressources,etc but you have to analyze the litterature so as to understand the consequences of war and then build a theory. you need to test also the causal inference impact.
The significance of variables can only be quantified after the model is built. Therefore, it is necessary to conduct a pilot study, identify the most significant variables based on its results, and then conduct a basic study on them. Ask analysis and the Eidos system are suitable for this.