The alert was sparked following a report to police shortly before 9.30pm.
A suspicious object had been found at the door of flats at Doon Park in the Killynure area, prompting a number of homes to be evacuated.
Army bomb experts attended the scene and dealt with the device.
"A motive for the incident has not been established," a police spokesperson said.
Alliance councillor Geraldine Rice condemned those responsible and said lives had been put at risk.
"Anybody passing close by could have been severely injured, or worse, if it detonated," she said.
"The people who left this bomb in such a residential area obviously have no regard for the consequences of their actions.
"There can be no justification for the actions of such a callous group of individuals."
Detectives at Castlereagh are appealing for information.