Insurgent Learning

We study a model of insurgent learning during a counterinsurgency campaign. We test empirical implications of the model using newly declassified microdata documenting improvised explosive devices (IEDs) in Afghanistan from 2006 to 2014. This period was characterized by substantial US investments in anti-IED technology and equipment. We find no evidence of decreasing effectiveness of IEDs across time. Qualitative evidence suggests that this is due to innovations in IED devices and tactics. Our results are robust to numerous alternative specifications, and yield insights on a technological revolution in insurgent violence—the proliferation and evolution of IEDs—with implications for scholarship on civil conflict and future investment in tactical countermeasures.