The device was found on the Friary Road area of Armagh
A bomb made safe by the Army in Armagh was a "horizontal mortar type device", police have said.
They said it was capable of destruction and death and was designed to kill police officers.
An alert began in the Friary Road area of the city after police received a report late on Wednesday night that a suspicious device had been left.
Nearby homes were evacuated and the road was closed. It has since been reopened.
District Commander Chief Superintendent Alasdair Robinson said it was "a viable explosive device capable of causing serious injury or indeed death".
He said the initial call by a member of the public helped them pinpoint exactly where the device had been left.
"I have no doubt the aim was to kill police officers engaged in providing a community service to the area," he said.
"The actions of both our local police officers and of the Army technical officers are in stark contrast to that of the reckless criminal terrorists who abandoned this device close to private homes placing the lives of those living in this area at risk."
In July, police in the area came under attack with missiles and paint during another security alert in which a minor explosion occurred.
Three members of a Continuity IRA gang were each jailed for 15 years in September for a plot to kill police officers with a mortar bomb in Lurgan, County Armagh.
A live mortar, complete with launching tube, was found near the Cornakinnegar Road on 5 April 2007.