Can you explain what's the reason? You can say positive as well as negative reasons.
I think the most common reason for war is the urge to capture resources owned by another jurisdiction. For example, the USA frequently goes to war to secure access to energy resources.
This is one of the reasons, the other subordination of the government of the country under its jurisdiction well and getting profit from it and expanding business in this country including export and import. In general, it's just enrichment and personal motives.