Sanctions in networks

In this paper we contribute to the sender-target models of sanctions by explicitly incorporating the linkages (social, political, or economic) that bind the sender and target to other agents. Given any network model and architecture, we draw attention to two factors that play a key role in determining the efficacy of sanctions in reducing the frequency of violations. These are, respectively, strategic complementaritiesbetween the sanctioning action (deleting link with target) and number of direct links of the sender, and the externalities imposed on the sender by third parties. We examine the role played by these factors both in the short run (when links can only be deleted) and the long run (when links can also be added), as well as when sanctions are unilateral (the sender can only delete own links) or multilateral (the sender can impose on common allies to sever links to the target). Our analysis allows an active role to the target to build an opposing coalition to deflect sanctions and to third parties to engage in “sanction busting. ” It also extends to multiple senders and targets, existence of interest groups within sender and target with dissimilar objectives, and signed networks allowing both antagonistic and cordial bilateral relationships.