Civil War and Foreign Influence∗

We use different variations of the canonical bargaining model of civil war to illustrate why a potential alliance with a third (foreign) party that affects the probability of winning the conflict can trigger or prolong an already existing civil war. We explore both political and economic incentives for a third party to intervene. The explicit con-sideration of political incentives leads to two predictions that allow for identifying the influence of foreign intervention on civil war incidence. Both predictions are confirmed for the case of the U.S. as a poten-tially intervening nation: (i) civil wars around the world are more likely under Republican governments and (ii) the probability of civil wars decreases with U.S. presidential approval rates. These results withstand several robustness checks and, overall, show that foreign influence is a sizable driver of conflict around the world