Oil well fires rage outside Kuwait City in the aftermath of the First Gulf War. (Photo: Everett Historical/Shutterstock)

It's not just some superstition: Oil really is behind a great deal of military conflict. Third-party states are more likely to intervene in civil wars when the conflict is in an oil-rich nation or the third party is particularly oil-thirsty, new research finds.

Civil wars such as the ongoing Syrian conflict are more and more the dominant form of armed conflict, and as such scholars have offered a variety of explanations as to why they happen—from post-colonial disagreements to El Niño, along with old standbys like ethnic conflicts. That said, students of war have said relatively little about why other countries intervene, and whatever explanations do exist often emphasize the history of a particular conflict, say, the 1978 Vietnamese invasion of Cambodia, rather than develop a broader theory of intervention. When researchers do look at intervention, the focus is on security or humanitarian concerns. It's rare for researchers to focus on economic considerations.

Third parties are more likely to enter into civil conflicts when they have sufficient military power and are thirsty for oil, and, of course, when there's a great deal of oil at stake.

That's a serious oversight, argue academics Vincenzo Bove, Kristian Skrede Gleditsch, and Petros Sekeris in the Journal of Conflict Resolution, especially considering that external powers—states and international organizations such as the United Nations—intervened in two of every three civil wars in the second half of the 20th century. "This is all the more remarkable as economic incentives are often held to exert a crucial role on the onset and duration of civil war," they write.

To investigate how economic incentives affect the chances of intervention, the trio constructed an economic model of conflict in which there are a small number of oil-producing nations, one of which is in the midst of a civl war, and a large number of countries with no oil to pump out of the ground. Intuitively, their analysis suggests that the richer a government is in oil reserves and the fewer oil-producing states there are, the more likely other states will intervene, even if the intervening state is itself an oil-producing nation. Similarly, states are more likely to intervene when they import more oil.

It remained to be seen, however, whether those predictions are actually borne out in the data on civil wars. To find out, the researchers collected data on civil war interventions, oil reserves, oil prices over time, and a number of other factors. Taking into account factors like a potential intervener's ability to swing the war in their own favor, the team confirmed their predictions—third parties are more likely to enter into civil conflicts when they have sufficient military power and are thirsty for oil, and, of course, when there's a great deal of oil at stake.

Those results may shed light on other international conflicts and military aid as well, like ongoing U.S. military aid in the Arabian peninsula. The team is blunt: "This military and political support is at least in part motivated to ensure that countries on the Arabian Peninsula maintain crude oil prices within a target range." Who the players in future interventions are, though, may change alongside the demand for oil.