Is the Phone Mightier Than the Sword? Cellphones and Insurgent Violence in Iraq

Does improved communication provided by modern cellphone technology affect the rise or fall of violence during insurgencies? A priori predictions are ambiguous; introducing cellphones can enhance insurgent communications but can also make it easier for the population to share information with counterinsurgents and creates opportunities for signals intelligence collection. We provide the first systematic micro-level test of the effect of cellphone communication on conflict using data on Iraq's cellphone network (2004-2009) and event data on violence. We show that increased mobile communications reduced insurgent violence in Iraq, both at the district level and for specific local coverage areas. The results provide support for models of insurgency that focus on noncombatants providing information as the key constraint on violent groups and highlight the fact that small changes in the transaction costs of cooperating with the government can have large macro effects on conflict.