Several families have been evacuated from their homes in west Belfast while army bomb experts dealt with a suspect device.
The object, which was found at Springbank Close in Poleglass, was taken away for examination.
Police later said that although it did not contain explosives, it was still a "viable device".
The PSNI in the area liaised with local representatives after petrol bombs and stones were thrown at officers.
Public transport was diverted away from the area while the disturbances continued.