Supt Greg Blain says he has no doubt people would have died
A 300lb car bomb has been found in County Down five days after a telephoned warning claimed a device had been left in Castlewellan village.
Security forces discovered an abandoned car on Dublin Road on Saturday. Several controlled explosions were carried out on what police called "suspect items".
It is thought the bomb was planted by dissident republicans who were trying to target the Ballykinler army base.
Supt Greg Blain said it was a "large explosive device".
He added that its detonation would have caused "substantial damage and loss of life".
Supt Blain said someone claiming to be a member of a dissident republican organisation had called a local newspaper to warn about the bomb.
"They... abandoned it in an area close to local houses and schools, and then phoned through vague warnings about the locality and nature of the threat," he said.
"They placed the lives of every man, woman and child in the area at risk."
South Down Stormont Assembly member Margaret Ritchie said those behind the bomb deserved nothing but contempt from the community.
"For five days [people in the area] have been worried and suffered massive inconvenience, having to take long detours to get to work or bring children to school.
"Those who planted it should be in absolutely no doubt - we are not going back to the past, even if they are locked in it."