Ardoyne bomb was 'mortar type' device
A bomb found in the Ardoyne area of north Belfast is believed to have been a mortar type device that could have been used to target a police vehicle.
The police have said it put the lives of people in the area at risk.
They have appealed for help to catch those responsible.
More than 30 families were moved out of their homes for several hours on Thursday after police discovered the device at the back of a house in Jamaica Street.
The police confirmed that an army bomb disposal team had made safe a "substantial viable device".
Ch Insp Andrew Freeburn said both he and the community in north Belfast were "extremely angry that somebody would put the lives of the community at risk in this way".
"I would ask people to transform that anger into action," he added.
"If you know anything about this incident please come forward."
The Police Service of Northern Ireland's Area Commander for north Belfast said the device was "intended to murder."
He said: "Once again the community of north Belfast have been disrupted and the lives of residents put at risk by an element intent on causing as much loss of life and disruption as they can.'Ludicrous act'
"The people who carried this out showed a callous disregard for the lives of everyone in our community.
"This is a residential area and we could have been looking at serious tragedy here."
Ch Insp Freeburn thanked people for their patience during the security operation. Those families who were moved have now returned to their homes.
The BBC's Andy Martin in Belfast says Ardoyne is a predominantly republican area of the city in which there are significant numbers of dissident republicans, including members of Oglaigh na hEireann which security forces have described as the most dangerous of the dissident factions.
Sinn Fein councillor Gerard McCabe condemned those who had shown no regard for the community in Ardoyne.
"This was a ludicrous act for anyone to leave a device somewhere where an innocent person could be seriously hurt or even killed," he said.
"It has caused a massive disruption for the people of the lower part of Ardoyne."