Estimating the Impact of Drone Strikes on Civilians Using Call Detail Records

Drone strikes are a fixture of US counter-terrorism policy, often advertised as ‘surgical’ alternatives to ground operations. Drone strikes’ effects, however, are less precise than proponents suggest. Using data from over 12 billion call detail records from Yemen between 2010 and 2012, we show that the US drone campaign significantly disrupted civilian lives in previously-unmeasured ways. Strikes cause large increases in civilian mobility away from affected areas and create immediate, durable displacement: mobility among nearby individuals increases 24 percent on strike days, and average distance from the strike region increases steadily for over a month afterward, signifying prolonged displacement for thousands of individuals. Strikes are disruptive regardless of whether they kill civilians, though effects are larger after civilian casualties. Our findings suggest that even carefully targeted drone campaigns generate collateral disruption that has not been weighed in public debate or policy decisions about the costs and benefits of drone warfare.