The Impact of Drone Warfare on Suicide Bombings in Pakistan

Some analysts argue that US drone strikes targeting militants in the North Waziristan (NW) region of the erstwhile Federally Administered Tribal Areas (FATA) of Pakistan reduced militant activity. Others argue that these CIA-led strikes increased this activity. Cause and effect are difficult to disentangle because common underlying factors may drive both forms of violence. We use weather to identify a positive and large, short-run causal effect of drone strikes in NW on suicide attacks nationwide in Pakistan. Specifically, we use cloud cover and precipitation data for NW, plus a dummy variable for a specific drone base closure, to instrument for drone strikes in NW between July 2008 and the end of 2016 and identify a casual effect on suicide bombings in the whole country during this period. The instruments embody the idea that drone strikes, but not suicide bombings, rely on good weather and appropriate air bases for their feasibility and effectiveness. This causal apparatus enables us to test the theory that during this period prepared-in-advance suicide attacks were green lit as visible replies to drone strikes. We find that each drone strike causes, on average, at least 1 suicide bombing within the subsequent month. We characterize 18-26 percent of all suicide bombings from July 2008 through 2016 as reactions to drone strikes. These reaction attacks mainly hit security targets, although they also cause many civilian fatalities. Strikes that eliminate militants’ leadership provoke particularly large reactions, consistent with the idea that militants try to demonstrate that they are strong and fighting back, especially when they are hit at the highest levels.