If we cooperate together, we intervene together: Defense cooperation agreements and support to conflict parties

As governments increasingly turn to defense cooperation agreements (DCAs) to institutionalize defense relations, there is little scholarly knowledge of the impact of these agreements in civil wars. Are DCA partners more likely to militarily intervene in civil conflicts together compared with countries without DCAs? While studies show that formal alliance commitments impact the likelihood of parties participating in foreign interventions, DCAs have received little attention in the literature even though DCAs between partner states are signed frequently and subject to change. This study argues that partners in DCAs are likely to provide external military support to the same conflict parties. Our theoretical model suggests that DCAs provide an arena for socialization where governments and military organizations that are DCA partners have repeated interactions. As a result of socialization, their foreign policy goals increasingly align, including their approach to military intervention in foreign conflicts. With access to similar weapons material, military training, and information, DCAs facilitate joint interventions between partner states. Examining the probability of intervention in civil conflicts during the period of 1980–2009, we find that countries that are DCA partners are more likely to provide military assistance to the same warring parties compared with countries without DCAs.