Residents of more than 400 homes who had been evacuated in the Rivenwood area of Newtownards since the device was discovered last Thursday because of a large Second World War-era bomb have been able to return home.
Police and Army bomb experts had been at the site where a sand-filled structure was constructed around the device while it was considered if it should be removed or made safe there.
District Commander for Ards and North Down Superintendent Johnston McDowell confirmed a controlled explosion had taken place at 3.38pm.
Video: PSNI