The suspect device found earlier today at Pigeon House Road in Dublin was viable, according to a spokesman for the Defence Forces.
A man in his 20s was arrested following the discovery of the device shortly after 1pm. A Taser device was used during the arrest.
The Army bomb disposal unit was brought in to deal with the device and the area was sealed off for a number of hours.
The man is being held at Blackrock Garda Station under Section 30 of the Offences Against the State Act and can be detained for up to 72 hours.