abstract: How do foreign powers disengage from a conflict? We study the recent largescale security transition frominternational troops to local forces in the context of the ongoing civilconflict in Afghanistan. We construct a new dataset that combines informationon this transition process with declassifiedconflict outcomes and previously unreleased quarterly survey data. Ourempirical design leverages the staggered roll-out of the transition onset,together with a novel instrumental variables approach to estimate the impact ofthe two-phase security transition.We find that the initial security transfer to Afghanforces is marked by a significant, sharp and timely decline in insurgentviolence. This effect reverses with the actual physical withdrawal of foreigntroops. We argue that this pattern is consistent with a signaling model, inwhich the insurgents reduce violence strategically to facilitate the foreignmilitary withdrawal. Our findings clarify the destabilizing consequences ofwithdrawal in one of the costliest conflicts in modern history and yieldpotentially actionable insights for designing future security transitions.